Chapter IX: Introduction: By L. H. Bailey (2)

The transformation of one of these young insects into an adult is one of the most interesting observation lessons that can be imagined for a warm spring morning. If a dragon-fly nymph should signify its intention of changing its form in my school-room, I should certainly suspend all ordinary work and attend to him alone. Each child should see if possible this wonderful transfiguration.

Floating in the water of a pond or stream one may find a little bundle of grass or weed stems, with perhaps a tiny pebble clinging to the mass. Close examination will prove this to be the "house-boat" of one of our insect neighbors, the caddice-worm. Contrasting strangely with the untidy exterior is the neat interior, with its lining of delicate silk, so smooth that the soft-bodied creature which lives inside is safe from injury. The commonest of the many forms of houses found here are those illustrated in Figs. 76 and 77. These will find all they wish to eat in a well-stocked aquarium. When full grown they will leave the water as winged creatures, like Fig. 78, and return to its depths no more.

There is surely no lack of material furnished by Mother Nature for the study of aquatic life. Every one who really believes in its usefulness can have an aquarium, and will feel well repaid for the time and effort required when the renewed interest in nature is witnessed which this close contact with living beings brings to every student. Let us take hold with a will, overcome the difficulties in the way, and teacher and pupils become students together.

LEAFLET XIII.

A STUDY OF FISHES.[17]

BY H. D. REED.

[17] Nature-Study Quarterly, No. 8: Leaflet 21. January, 1901.

The first forms of animal life which attract the young naturalist's attention are doubtless the birds. These are most interesting to him because of their beautiful colors, their sweet songs, and the grace with which they fly. But who has watched the fishes in a brook or an aquarium and is not able to grant them a place, in beauty, grace and delicate coloration, equal to the birds? To be sure, fishes cannot sing, yet there are so many other interesting facts in connection with their habits and life-histories that it fully makes up for their lack of voice.

THE PARTS OF A FISH.

While observing a living fish and admiring its beauty, it will probably occur to some of us that a fish consists only of a head and tail. Yet this is not all. Between the head and tail is a part that we may call the trunk. It contains the digestive and other organs. There is no indication of a neck in a fish. Any such constriction would destroy the regular outline of the animal's body and thus retard the speed with which it moves through the water. But head, trunk and tail are not all. There are attached to the outer side of the fish's body certain appendages that are called fins.

Before discussing some of the different kinds of fishes and their habits, it will be necessary to learn something about fins, for the fins of all fishes are not alike. When a fish moves through the water, it bends its tail first to one side and then to the other. This undulatory movement, as it is called, pushes the fish's body ahead. One can observe the movements easily upon a specimen kept alive in an aquarium jar. At the extreme end of the tail there is a broad, notched fin which aids the tail in propelling and steering the body. We will call this the _tail_ or _caudal_ fin (Fig. 79 B). In most of our common fishes there are seven fins--six without the caudal. The first of these six is a large fin situated near the middle of the back. This is the _back_ or _dorsal_ fin (Fig. 79 A). Sometimes we may find a fish that has two dorsal fins. In this case the one nearest the head is called first dorsal and the next one behind it the second dorsal. Near the head, in a position corresponding to our arms, is a pair of fins which are called the _arm_ or _pectoral_ fins (Fig. 79 E). Farther back towards the tail, on the under side of the fish, is another pair, corresponding in position to the hind legs of a quadruped. This pair is called the _leg_ or _pelvic_ fins (Fig. 79 D). Just behind the pelvic fins is a single fin, situated on the middle line of the body. This is the _anal_ fin (Fig. 79 C). The pectoral and pelvic fins are called paired fins because they are in pairs. The others which are not in pairs are called median fins, because they are situated on the middle line of the body. The paired fins serve as delicate balancers to keep the body right side up and to regulate speed. They are also used to propel the body backwards. After naming the different fins of the fish in the schoolroom aquarium, it will be interesting to observe the uses of each.

On the side of the body, extending from the head to the caudal fin, is, in most fishes, a line made up of a series of small tubes which open upon the surface. This is called the _lateral line_, and acts in the capacity of a sense organ (Fig. 79 L). Is the lateral line straight or curved? Does it curve upwards or downwards? Does the curvature differ in different kinds of fishes? Do all the fishes you find possess a lateral line? Is the lateral line complete in all fishes, _i. e._, does it extend from the head to the caudal fin without a single break?

WHERE FISHES SPEND THE WINTER.

As winter approaches and the leaves fall and the ground becomes frozen, the birds leave us and go farther south into warmer climates where food is more abundant. We are all familiar with this habit of the birds, but how many of us know or have even wondered what the fishes have been doing through the cold winter months while the streams and ponds have been covered with ice? Before the warmth of spring comes to raise the temperature of the streams, let us go to some familiar place in a brook where, during the summer, are to be found scores of minnows. None are to be found now. The brook shows no signs of ever having contained any living creatures. Suppose we go farther up or down the stream until we find a protected pool the bottom of which is covered with sediment and water-soaked leaves. With our net we will dip up some of the leaves and sediment, being sure that we dip from the very bottom. On looking over this mass of muddy material we may find a fish two or three inches long, with very fine scales, a black back, a silvery belly and a blackish or brown band on the side of the body extending from the tip of the nose to the tail. This is the _Black-nosed Dace_ (Fig. 80). If specimens of this fish are caught very early in the spring, one will be able to watch some interesting color changes. As the spawning time approaches, the dark band on the sides and the fins change to a bright crimson. Sometimes the whole body may be of this gaudy color. During the summer the lateral band becomes orange. As the season goes, the bright colors gradually fade until finally, in the fall and winter, the little black-nose is again clothed in his more modest attire. A great many of the fishes, and especially the larger ones, seek some deep pond or pool in the stream at the approach of winter, and remain near the bottom. If the pond or stream is so deep that they do not become chilled they will remain active, swimming about and taking food all winter. But when the stream is very shallow and the fishes feel the cold, they settle down to the bottom, moving about very little and taking little or no food. The carp collect in small numbers and pass the winter in excavations that they make in the muddy bottom. If the débris thrown up by the water across the marshy end of a lake be raked over during the winter, one will probably find some of the smaller catfishes spending the season in a semi-dormant state.

Some interesting experiments may be tried with the fishes in the aquarium jar. Keep them for a few days where it is cold and then bring them into a warmer room and note the difference in their activity.

THE COMMON CATFISH OR BULLHEAD.

This sleepy old fellow differs in many respects from most of our common fishes. He has no scales. About the mouth are eight long whisker-like appendages, called barbels (Fig. 81). Perhaps he is called catfish because he has whiskers about his mouth like a cat. Any one who has ever taken a catfish from the hook probably knows that care is needed in order not to receive a painful prick from the sharp spines in his pectoral and dorsal fins.

There is nothing aristocratic about the catfish. In warm pools and streams where the water is sluggish and the muddy bottom is covered with weeds, he may be found moving lazily about in search of food. His taste is not delicate. Animal substance, whether living or dead, satisfies him. When in search of food he makes good use of his barbels, especially those at the corners of his mouth, which he uses as feelers. The catfish will live longer out of water than most of our other food fishes. They will live and thrive in water which is far too impure for "pumpkin seeds" or bass. They spawn late in the spring. The mother fish cares for her young much as a hen cares for her chickens. When they are old enough to take care of themselves, she weans them.

THE COMMON SUNFISH OR PUMPKIN SEED.

Some evening just at sunset visit a quiet pool in a nearby stream. Drop in your hook baited with an "angle worm" and presently the dancing cork shows that you have a "bite." On "pulling up" you find that you really have a fish. It is a beautiful creature, too--thin flat body shaped something like the seed of a pumpkin. His back is an olive green delicately shaded with blue. His sides are spotted with orange, while his belly is a bright yellow. His cheeks are orange-color streaked with wavy lines of blue. Just behind his eye on his "ear-flap" is a bright scarlet spot. This is the common _Sunfish_ or _Pumpkin Seed_ (Fig. 82). He is a very beautiful, aristocratic little fellow, "looking like a brilliant coin fresh from the mint."

Keep him alive in an aquarium jar with a shiner. Compare the two fishes, as to the size and shape of their bodies and fins. Feed them different kinds of food, such as worms, insects and crackers, and try to discover which they like best and how they eat.

The sunfishes prefer quiet waters. They lay their eggs in the spring of the year. The male selects a spot near the banks of the stream or pond where the water is very shallow. Here he clears a circular area about a foot in diameter. After making a slight excavation in the gravel or sand, the nest is completed. The eggs are then deposited by the female in the basin-like excavation. He watches his nest and eggs with great diligence, driving away other fishes that chance to come near.

THE BLACK BASSES.

The black basses are not usually found in small streams where it is most pleasant for teachers and pupils to fish. They are fishes that seek the rivers and lakes. There are two kinds of black bass, the _Large-mouthed_ and the _Small-mouthed_. As the name indicates, the two may be distinguished by the size of the mouth. In the large-mouthed black bass the upper jaw extends to a point behind the eye, while in the small-mouthed species it extends to a point just below the middle of the eye (Fig. 83).

Both kinds of black bass may be found in the same body of water. The character of the bottoms over which they are found, however, differs. The small-mouthed prefers the stony bars or shoals. The large-mouthed, on the contrary, selects a muddy bottom grown over with reeds. They feed upon crayfish ("crabs"), minnows, frogs, worms, tadpoles and insects. Our black basses are very queer parents. They prepare a nest in which the eggs are deposited. Both male and female are very courageous in the defense of their eggs and young. As soon as the young fishes are able to take care of themselves the parent fishes leave them, and after that time may even feed upon their own children.

THE STICKLEBACK.

The sticklebacks are queer little fellows indeed (Fig. 84). The slender body, extremely narrow tail, and the sharp, free spines in front of the dorsal fin, give them at once the appearance of being both active and pugnacious little creatures. The sticklebacks are detrimental to the increase of other fishes since they greedily destroy the spawn and young of all fishes that come within their reach. They build nests about two inches in diameter, with a hole in the top. After the eggs are laid the male defends the nest with great bravery. The little five-spined brook stickleback in the Cayuga Lake basin, N. Y., is most commonly found in stagnant pools, shaded by trees, where the water is filled with decaying vegetable matter,--the so-called "green frog-spawn" (spirogyra), and duck weed. If you supply the sticklebacks with plenty of fine vegetable material, you may induce them to built a nest in the aquarium jar, but they must be caught and placed in the jar early in the season before they spawn.

THE JOHNNY DARTERS.

In New York State, every swift stream which has a bed of gravel and flat stones ought to contain some one of the Johnny darters, for there are a great many different kinds (Fig. 85). They are little creatures, delighting in clear water and swift currents where they dart about, hiding under stones and leaves, or resting on the bottom with their heads up-stream. The body of a darter is compact and spindle-shaped, gradually tapering from the short head to a narrow tail. The eyes are situated nearly on top of the head. The color of the darters varies greatly with the different kinds. Some are very plain, the light ground color being broken only by a few brown markings. Others are gorgeous in their colorings, it seeming as if they had attempted to reproduce the rainbow on their sides. Such kinds are indeed very attractive and are ranked with the most beautifully colored of all our common fishes. When a darter swims, he appears bird-like, for he flies through the water much as a bird flies through the air. He does not use his tail alone in swimming, as the catfish, the sunfish, the stickleback, and most of the other fishes do, but flies with his pectoral fins.

You surely must have a Johnny darter in your aquarium jar. The Johnnies are true American fishes. Though small, they face the strong currents and eke out a living where their larger cousin, the yellow perch, would perish. There are many interesting facts which may be learned from the Johnny darters when kept alive in an aquarium. When not actually moving in the water, do the Johnnies rest on the bottom of the jar or remain suspended in the middle apparently resting on nothing, as the other aquarium fishes do? When a fish remains still in the middle of the jar he does so because he has a well-developed air-bladder to help buoy him up, and when a fish dies it is the air-bladder which causes him to turn over and rise to the top. Now if the Johnnies always rest on the bottom of the jar when not swimming and if one happens to die and does not rise to the top we may know that, if he has an air-bladder at all, it is only a vestigial one. It would be interesting also to find out for ourselves whether a Johnny darter can really "climb trees" (I mean by trees, of course, the water plants in the aquarium jar), or if he can perch upon the branches like a bird.

THE MINNOWS.

All the small fishes of the brooks are called minnows, or more often "minnies," by the boy fisherman. The boy believes that they grow into larger fishes. This is not true. The minnows are a distinct group of fishes and, for the most part, small ones. They do not grow to be bass or pike or sunfishes or anything else but minnows. Some of the minnows, however, are comparatively large. Two of these are the _Creek Chub_ (Fig. 80), and the _Shiner_ (Fig. 80). The chub is the king of the small brooks, being often the largest and most voracious fish found in such streams. His common diet probably consists of insects and worms, but if very hungry he does not object to eating a smaller fish. During the spawning season, which is springtime, the male chub has sharp, horny tubercles or spines developed upon the snout. We are able to recognize the creek chub by means of a black spot at the front of the base of the dorsal fin.

The shiner or red-fin has much larger scales than the chub. The back is elevated in front of the dorsal fin, giving him the appearance of a hump-back. His sides are a steel-blue with silvery reflections. While the shiner is not the largest, it is almost everywhere one of the most abundant brook fishes. In spring the lower fins of the male become reddish. Like the chub, he has small horny tubercles developed on the snout.

RANDOM NOTES.

Did you ever see a fish yawn? Watch a shiner in your aquarium. Sometimes you may see him open his mouth widely as though he was very sleepy. Again you may find him resting on the bottom of the jar taking a nap. Fishes cannot close their eyes when they sleep for they have no eyelids.

A convenient way to collect fishes for the schoolroom aquarium is to use a dip net. The ordinary insect net will do, but it is better to replace the cheese-cloth bag by a double thickness of mosquito-bar, thus enabling one to move the net through the water more rapidly. By dipping in the deep pools, among grasses and under the banks with such a net one can soon obtain fishes enough to stock an aquarium (Fig. 86). The aquarium jar should never be placed in the sun. It is better to have only three or four fishes in an aquarium at one time. Some flat stones on the bottom of the jar will afford them convenient hiding places.

For further notes on aquaria, consult Leaflet No. XII.

LEAFLET XIV.

THE OPENING OF A COCOON.[18]

BY MARY ROGERS MILLER.

[18] Nature-Study Quarterly, No. 4: Leaflet 17. March, 1900.

Among the commonest treasures brought into the schools by children in the fall or winter are the cocoons of our giant silk-worms. If one has a place to put them where the air is not too warm or dry, no special care will be necessary to keep them through the winter. Out-door conditions must be imitated as nearly as possible. If early in the fall one is fortunate enough to meet one of these giants out for a walk, it is the simplest thing in the world to capture him and watch him spin his marvelous winter blanket. Two members of this family of giant insects are quite common in this state, the largest the Cecropia, called sometimes the Emperor, and the Promethea.

The Cecropia moth often measures five or six inches across--a veritable giant. Its main color is dusty brown, with spots and bands of cinnamon brown and white. On each wing is a white crescent bordered with red and outlined with a black line. The body is heavy and covered with thick, reddish-brown hairs, crossed near the end with black and white lines. On its small head are two large feathery feelers or antennæ. The Cecropia moth emerges from the cocoon, full grown, in early summer, when out of doors. Those kept in the house often come out as early as March. The eggs are deposited by the adults upon apple, pear, cherry, maple and other shade and fruit trees. Professor Comstock says that the spiny caterpillars which hatch from the eggs in about two weeks, are known to feed upon the leaves of some fifty species of plants. One could therefore hardly make a mistake in offering refreshment to these creatures, since they are anything but epicures. The full-grown caterpillar, having spent the summer eating and growing, with now and then a change of clothes, is often three inches long and an inch in diameter. It is a dull bluish green in color. On its back are two rows of wart-like protuberances (tubercles), some yellow, some red, some blue. As there is nothing else in nature which is just like it, one need have no difficulty in recognizing the Cecropia in its different phases.

The cocoon which this giant silk-worm weaves is shown in Fig. 87. It may be found on a twig of some tree in the dooryard, but sometimes on a fence-post or equally unexpected place. Inside the cocoon the brown pupa, alive but helpless, waits for spring.

After the moth comes out it is interesting to examine the structure of the cocoon, and to discover how the moth managed to free itself without destroying the silken blanket (Fig. 88).

Swinging loosely from last summer's twigs in lilac bushes, and on such trees as wild cherry and ash, one often finds the slender cocoons of the Promethea moth (Fig. 89). We cannot help admiring the skill and care displayed by the spinner of this tidy winter overcoat. The giant silk-worm which spun it chose a leaf as a foundation. He took care to secure himself against the danger of falling by fastening the leaf to the twig which bore it by means of shining strands of silk. It is easy to test the strength of this fastening by attempting to pull it loose from the twig.

The moths which come from these cocoons do not always look alike, yet they are all brothers and sisters. The brothers are almost black, while the wings of the sisters are light reddish brown, with a light gray wavy line crossing the middle of both wings. The margins of the wings are clay-colored. On each wing is a dark velvety spot. The adults emerge in spring and are most often seen in the late afternoon. Their flight is more spirited than that of the Cecropia, which moves very sedately, as becomes a giant.

The caterpillars of this species, the young Prometheas, feed during the summer on leaves of wild cherry, ash and other trees. They grow to be about two inches long, and are distinguished from others by their pale bluish green color and yellow legs. They also have rows of wart-like elevations on their backs, some black and shining, four of a bright red and one large and yellow near the hindmost end.

* * * * *

The life of these giant insects is divided into four distinct stages: the egg, deposited by the adult moth usually on or near the food plant; the larva, or caterpillar stage, when most of the eating and all the growing is done; the pupa, passed inside the cocoon woven by the larva; and the adult, a winged moth.

The life-cycle or generation is one year, the winter being passed in the pupa stage. The insect lives but a short time in the adult stage and the egg stage is but two or three weeks. Most of the summer is devoted to the caterpillar phase of its life.

These creatures are entirely harmless. They seldom appear in numbers sufficient to make them of economic importance.

LEAFLET XV.

A TALK ABOUT SPIDERS.[19]

BY J. H. COMSTOCK.

[19] Nature-Study Quarterly, No. 9: Leaflet 22. May, 1901.

Of all our little neighbors of the fields there are none that are more universally shunned and feared than spiders, and few that deserve it less. There is a wide-spread belief that spiders are dangerous, that they are liable to bite, and that their bites are very venomous. Now this may be true of certain large species that live in hot countries; but the spiders of the Northern United States are practically harmless.

It is true, spiders bite and inject venom sufficient to kill a fly into the wound made by their jaws. But they are exceedingly shy creatures, fearing man more than they are to be feared. If an observer will refrain from picking up a spider there is not the slightest danger of being bitten by one; and excepting a single uncommon species no spider is known in this part of the country whose bite would seriously affect a human being.

On the other hand, spiders do much to keep in check various insect pests, and hence must be regarded as our friends. It is, however, from a different point of view that we wish to look upon them at this time. It is as illustrations of remarkable development of instinctive powers, and of wonderful correlation of structure and habit, that we would have the reader study these creatures. The teacher of nature-study can find no more available or more fertile field from which to take subjects for interesting children in the world about us. Let us then put aside our fears and go into the fields and see whether we can learn something of the ways of these spinners.

THE FUNNEL-WEB WEAVERS.

Often on summer mornings the grass of the roadsides and fields is seen to be carpeted with little sheets of glistening silk, the webs of the grass-spider. None were observed the day before; and we wonder at the sudden appearance of this host of weavers. Later in the day the webs have vanished! Have the weavers rolled them up and carried them off? We remember that there was an especially fine one near the end of the veranda steps; we examine the place carefully and find that it is still there, but not so conspicuous as it was. The warm sun has dissipated the dew which rendered visible to our dull eyes the tapestry of the fields. Now that our eyes are opened we can find the webs everywhere and are impressed with a suspicion that perhaps ordinarily we see very little of what is around us.

We examine one of the webs carefully and find that it is a closely woven sheet made of threads running in all directions; that it is attached to spears of grass, and supported by numerous guy lines, and that from one side a funnel-like tube extends downwards. If, while we are watching, an insect alights on the sheet, there darts from the tunnel, where she was concealed, the owner of the web, a dark-colored spider; and the insect must be agile if it escapes.

If you attempt to catch the spider it retreats to its tunnel; and when you examine the tunnel the spider is not there. You find that the tube is open below, that there is a back door by which the spider can escape when hard pressed.

We call those spiders that makes webs of this kind _The Funnel-web Weavers_. They are long-legged, brown spiders, which run on the upper surface of their webs; these are usually made on grass, but sometimes they are found in the angles of buildings, and in quite high places.

THE COBWEB WEAVERS.

The webs that we most often find in the corners of rooms are of a different kind and are made by the members of a family known as _The Cobweb Weavers_. In these webs there is not such a definite sheet of silk as in those of the funnel-web weavers, but instead a shapeless maze of threads extending in all directions. Many of the cobweb weavers, however, make their webs in the fields on bushes, and weave in them a flat or curved sheet, under which the spider hangs back downward. The funnel-web weavers run right side up; the cobweb weavers hang inverted. Some of the cobweb weavers do not remain in their webs, but have a nest in a neighboring crack or corner, from which they rush to seize their prey, and sometimes there is a funnel-shaped tube leading to their nest. But these spiders differ from the true funnel-web weavers in running back downwards on the lower side of their webs.

THE ORB WEAVERS.

The spider webs that most often excite admiration are those in which the supporting threads radiate from a center like the spokes of a wheel, and bear a spiral thread. Such webs are known as orb-webs; and the family of spiders that make them, _The Orb Weavers_.

Few if any of the structures built by lower animals are more wonderful than these webs; but they are so common that they are often considered hardly worthy of notice. If they occurred only in some remote corner of the earth, every one would read of them with interest.

The webs or nets of the different species of orb weavers differ in the details of their structure; but the general plan is quite similar. There is first a framework of supporting lines. The outer part of this framework is irregular, depending upon the position of the objects to which the net is attached; but the central part is very regular, and consists of a number of lines radiating from the center of the net (Fig. 91). All of these supporting lines are dry and inelastic. Touch them with your pencil and you find that they neither stretch nor adhere to it. Upon these radiating lines there is fastened in a very regular manner a thread which is sticky and elastic. This will adhere to your pencil, and will stretch several times its normal length before breaking. Usually this sticky thread is fastened to the radiating lines so as to form a spiral; but a few species make nets in which it is looped back and forth. And even in the nets where the greater part of the thread is in a spiral there are in most cases a few loops near the lower margin (Fig. 91). Examine the next orb-web you find and see whether it is true in that case.

Many of the orb weavers strengthen their nets by spinning a zigzag ribbon across the center. This ribbon is made by spreading apart the spinnerets, the organs from which the silk is spun, and which will be described later. Ordinarily the tips of the spinnerets are held close together so that they form a single thread, but by spreading them apart many threads can be spun at once, thus forming a ribbon.

Some orb weavers are not content with making a simple zigzag band across the center of the net, but weave an elaborate bit of lace in this position. Fig. 92 is from a photograph of the center of the net of one of these spiders, which was found near Ithaca.

In studying the various kinds of orb-webs one should pay particular attention to the center of the web; for this part differs greatly in the webs of the different species. There is usually a _hub_ composed entirely of dry and inelastic silk woven in an irregular manner; outside of this there are several turns of a spiral thread which is also dry; this constitutes the _notched zone_, a name suggested by the fact that the spiral line is attached for a short space to each radius it crosses, thus giving the line a notched course. In many cases it is here, on the hub and the notched zone, that the spider waits for its prey; and it is obvious that sticky silk in this place would be objectionable. Between the notched zone and the _spiral zone_, the part furnished with the sticky spiral thread, there is a clear space, the _free zone_, crossed only by the radii. This gives the spider an opportunity to pass from one side of the web to the other without going around the entire web.

Some orb weavers do not wait upon the hub but have a retreat near one edge of the net, in which they hang back downwards. While resting in these retreats they keep hold of some of the lines leading from the net, so that they can instantly detect any jar caused by an entrapped insect.

When an insect in its flight touches one of the turns of the sticky line the line adheres to it, but it stretches so as to allow the insect to become entangled in other turns of the line. If it were not for this elasticity of the sticky line, most insects could readily tear themselves away before the spider had time to reach them.

In running over its net the spider steps upon the radii, carefully avoiding the sticky line; otherwise it would destroy its own net. The rapidity with which a spider can cross its net without touching the sticky line is remarkable.

In making its web an orb weaver first spins a number of lines extending irregularly in various directions about the place where its orb is to be; this is the outer supporting framework. Often the first line spun is a bridge between two quite distant points, as the branches of two separate bushes. How did the spider cross the gulf? It has no wings.

The bridge building can be easily seen on a warm summer evening, the time at which the spiders are most active repairing their old nets and building new ones. The spider lifts the hind end of its body and spins forth a thread; this is carried off by the wind, until, finally striking some object, it becomes fast to it. The spider then pulls in the slack line, like a sailor, and when the line is taut fastens it to the object on which it is standing, and the bridge is formed.

After making the outward framework, the radiating lines are formed. A line is stretched across the space so as to pass through the point which is to be the center of the orb. In doing this the spider may start on one side, and be forced to walk in a very roundabout way on the outer framework to the opposite side. It carefully holds the new line up behind it as it goes along, so that it shall not become entangled with the lines on which it walks; one or both hind feet serve as hands in these spinning operations; for, as the spider has eight feet, it can spare one or two for other purposes than locomotion. When the desired point is reached the slack is pulled in and the line fastened. The spider then goes to the point where the center of the orb is to be, and, fastening another line, it walks back to the outer framework, and attaches this line an inch or two from the first. In this way all of the radiating lines are drawn. The next step is to stay these radii by a spiral line, which is begun near the center, and attached to each radius as it crosses it. The turns of this spiral are as far apart as the spider can conveniently reach.

All of the threads spun up to this stage in the construction of the web are dry and inelastic. The spider now proceeds to stretch upon this framework a sticky and elastic line, which is the most important part of the web, the other lines being merely a framework to support it. In spinning the sticky line, the spider begins at the outer edge of the orb, and passing around it, fastens this line to each radius as it goes. Thus a second spiral is made. The turns of this spiral are placed quite close together, and the first spiral, which is merely a temporary support, is destroyed as the second spiral progresses. Fig. 93 represents a web in which the second spiral is made over the outer half of the radii. In this figure, _aa_ represents the temporary stayline; _bb_, the sticky spiral; and _cc_, the fragments of the first spiral hanging from the radii.

THE PARTS OF A SPIDER.

Spiders differ much in appearance from the true insects. In the insects the body is composed of three regions: the head; the thorax, to which the legs are attached; and the abdomen or hind part of the body (Fig. 94). In the spiders the head and thorax are grown together, forming a region which is known as the _cephalothorax_; to this the _abdomen_ is joined by a short, narrow stalk (Fig. 95). Spiders differ also from insects in the number of their legs, spiders having eight legs and insects only six.

Spiders have two pairs of jaws, which, except in the Tarantula family, move sidewise like the jaws of insects. The first pair of jaws are called the _mandibles_. Each mandible consists of two segments, a strong basal one and a claw-shaped terminal one, at the tip of which the poison gland opens (Fig. 96). The second pair of jaws is known as the _maxillæ_. These jaws are situated just behind the mandibles, one on each side of the mouth. Each maxilla bears a large feeler or _palpus_. These palpi vary greatly in form; frequently, especially in females, they resemble legs; hence many spiders appear to have five pairs of legs. In the male spiders the last segment of the palpus is more or less enlarged, ending in a complicated, knob-like structure (Fig. 97). It is thus easy to determine the sex of a spider by merely examining the palpi.

The greater number of spiders have four pairs of eyes (Fig. 98), but there may be only one, two, or three pairs; and certain cave spiders are blind. The eyes appear like little gems set in the front of the cephalothorax. They are most prominent in the jumping spiders, which stalk their prey on plants, logs, fences, and the sides of buildings.

The most characteristic feature of spiders is their spinning organs. The silk is secreted in glands within the abdomen, and while in the body it is a fluid. It passes out through the _spinnerets_, which are situated near the hind end of the abdomen. There are two or three pairs of spinnerets. These are more or less finger-like in form, and sometimes jointed (Fig. 99). Upon the end of each spinneret there are many small tubes, the _spinning tubes_ (Fig. 100), from which the silk is spun. Some spiders have as many as one hundred and fifty or two hundred of these spinning tubes on each spinneret.

Ordinarily the tips of the spinnerets are brought close together, so that all of the minute threads that emerge from the numerous spinning tubes unite to form a single thread. Hence this tiny thread, which is so delicate that we can see it only when the light falls on it in a favorable way, is composed of hundreds of threads. It is not like a rope, composed of separate strands; for all the minute threads fuse together into a single thread. The change in the silk from a fluid to a solid cord, strong enough to support the weight of the spider, must take place quickly after the silk comes in contact with the air on leaving the spinning tubes; the minute size of the threads coming from the spinning tubes doubtless facilitates this change.

Sometimes a spider will spread its spinnerets apart, and thus spin a broad ribbon-like band. We have seen a spider seize a large grasshopper which was entangled in its web, and rolling it over two or three times, completely envelop it in a sheet of silk spun from its spread-apart spinnerets. We have already described bands spun by orb weavers across the hub of the net in this way.

It is supposed that the two kinds of silk spun by the orb weavers are spun from different spinnerets, and that the viscid silk comes from the front pair. When this silk is first spun, the viscid matter forms a continuous layer of liquid on the outside of it. But very soon this layer breaks up into bead-like masses--in a way similar to that in which the moisture on a clothes line on a foggy day collects into drops (Fig. 101).

There are two families of spiders that have spinning organs differing from those of all other spiders. They have in front of the usual spinnerets an additional organ, which is named the _cribellum_ (Fig. 102, c). This bears spinning tubes like the other spinnerets, but these tubes are much finer. These spiders have also on the next-to-the-last segment of the hind legs one or two rows of curved spines; this organ is the _calamistrum_ (Fig. 103). By means of the calamistrum these spiders comb from the cribellum a band of loose threads which form a part of their webs.

THE CURLED-THREAD WEAVERS.

The spiders possessing a cribellum and a calamistrum represent two families, one of which makes irregular webs; the other, those which are of definite form.

An irregular web of a curled-thread weaver is shown in Fig. 104, from a photograph. In this web the framework is of ordinary silk; and upon this framework is placed a band of curled or tangled threads (Fig. 105). An insect alighting on a net of this kind is likely to get its feet caught in the tangled silk, and to be held fast till the spider can pounce upon it. Nets of this kind are found on bushes and on the sides of buildings.

There are two quite distinct types of regular webs made by spiders possessing a cribellum and a calamistrum. One is a round web which resembles at first sight those of the orb weavers; but it differs from the ordinary orb-web in that the spiral thread is made of curled or hackled silk. These webs are nearly horizontal, and are usually made between stones or in low bushes; they are not common.

The other type is represented by the web of the triangle spider. This web is most often found stretched between the twigs of a dead branch of pine or hemlock. At first sight it appears like a fragment of an orb-web (Fig. 106); but a little study will show that it is complete. The accompanying figure, by Dr. B. G. Wilder, who first described the habits of this spider ("Popular Science Monthly," 1875) illustrates the form of the web. It consists of four plain lines corresponding to the radiating lines of an orb-web, and a series of cross lines, which are spun by the cribellum and calamistrum. Each cross line is composed of two lines, about 1/500 of an inch apart. These double lines take the place of the curled threads woven by other members of the family to which the triangle spider belongs. From the point where the radiating lines meet, a strong line extends to one of the supporting twigs. Near this twig the spider rests, pulling the web tight so that there is some loose line between its legs, as shown in the enlarged figure. When an insect becomes entangled in one of the cross lines, the spider suddenly lets go the loose line so that the whole web springs forward, and the insect is entangled in other cross lines. The spider then draws the web tight and snaps it again. This may be repeated several times before the spider goes out upon the web after its prey.

The triangle spider is a tiny fellow, and so closely resembles the color of the dead branch near which it rests that it is very difficult to find; its web is more easily seen, though it usually requires careful searching to discover it.

THE MOTHERHOOD OF SPIDERS.

As a rule young spiders are forced to shift for themselves, and a very hard time they have; but of this we have not space to write. With spiders, the mother's care is devoted chiefly to furnishing protection to her helpless eggs. These are placed in silken sacs, which are often very elaborate in construction and protected with great care.

The most common egg-sacs are those found in the fields attached to stones and pieces of wood (Fig. 107). They are disk-shaped objects, silvery in color, and about the size of an old-fashioned three-cent piece.

The egg-sacs of the cobweb weavers can be found suspended in their webs; and those of the orb weavers, in various situations. Fig. 108 represents the large egg-sac of one of the orb weavers. This is made in the autumn, and contains at that season a large number of eggs--five hundred or more. These eggs hatch early in the winter; but no spiders emerge from the egg-sac until the following spring. If egg-sacs of this kind be opened at different times during the winter, the spiders will be found to increase in size but diminish in numbers as the season advances. In fact, a strange tragedy goes on within these egg-sacs: the stronger spiders calmly devour their weaker brothers, and in the spring those that survive emerge sufficiently nourished to fight their battles in the outside world.

The females of the _Running Spiders_ not only make a carefully constructed egg-sac, but also care for the young spiders for a time. The running spiders are the large dark-colored, hairy spiders, often found under stones and rubbish; they are so-called because they capture their prey by running. The females of most of the species (those of the genus _Lycosa_) drag after them their egg-sac, which is attached to the spinnerets (Fig. 109); and when the young hatch, they climb on their mother's back, and are carried about for a time.

One of the running spiders (_Dolomedes_) carries her egg-sac with her mandibles until the young are ready to emerge. At this time the mother fastens the egg-sac in a bush, and spins irregular threads about it, among which the young spiders remain for a time (Fig. 110). In the specimen figured, the egg-sac was concealed in the upper part of the web.

THE BALLOONING SPIDERS.

In warm autumn days, innumerable threads can be seen streaming from fences, bushes, and the tips of stalks of grass, or floating through the air. These are made by the _Ballooning Spiders_, which are able to travel long distances, hundreds of miles, through the air by means of these silken threads.

The ballooning spider climbs to some elevated point, and then, standing on the tips of its feet, lifts its body as high as it can, and spins out a thread of silk. This thread is carried up and away by a current of air. When the thread is long enough the force of the air current on it is sufficient to bear the spider up. It then lets go its hold with its feet and sails away. That these spiders travel long distances in this manner has been shown by the fact that they have been seen floating through the air at sea far from land.

LEAFLET XVI.

LIFE HISTORY OF THE TOAD.[20]

BY S. H. GAGE.[21]

[20] Teachers' Leaflet, No. 9, May, 1897.

[21] It was the desire of the author to tell the story of this leaflet in pictures as well as in words, and he wishes to express his appreciation of the enthusiasm and ability with which the illustrations were executed by Mr. C. W. Furlong.

In this edition are added half-tone reproductions of photographs to bring out more completely the life story.

On account of its economic importance, and because the marvelous changes passed through in growing from an egg to a toad are so rapid that they may all be seen during a single spring term of school, the common or warty toad has been selected as the subject of a leaflet in nature-study. Toads are found everywhere in New York, and nearly everywhere in the world; it is easy, therefore, to get abundant material for study. This animal is such a good friend to the farmer, the gardener, the fruit-grower, the florist and the stock-raiser that every man and woman, every boy and girl, ought to know something about it.

Furthermore, it is hoped and sincerely believed that the feeling of repugnance and dislike, and the consequent cruelty to toads, will disappear when teachers and children learn something about their wonderful changes in form, structure and habits, and how harmless and helpful they are. Then, who that knows of the chances, the dangers and struggles in the life of the toad, can help a feeling of sympathy; for after all, how like our human life it is. Where sympathy is, cruelty is impossible, and one comes to feel the spirit of these beautiful lines from Coleridge's "Ancient Mariner:"

"_He prayeth best who loveth best
All things both great and small;
For the dear God who loveth us
He made and loveth all._"

It was William Harvey, the discoverer of the circulation of the blood, who first clearly stated the fact that every animal comes from an egg. This is as true of a toad as of a chicken.

The toad lives on the land and often a long way from any pond or stream, but the first part of its life is spent in the water; and so it is in the water that the eggs must be looked for. To find the eggs one should visit the natural or artificial ponds so common along streams. Ponds from springs or even artificial reservoirs or the basins around fountains, also may contain the eggs. The time for finding the eggs depends on the season. The toad observes the season, not the almanac. In ordinary years, the best time is from the middle of April to the first of May.

One is often guided to the right place by noticing the direction from which the song or call of the toad comes. The call of the toad is more or less like that of the tree toads. In general it sounds like whistling, and at the same time pronouncing deep in the throat, bu-rr-r-r-r-. If one watches a toad while it makes its call, one can soon learn to distinguish the sound from others somewhat similar. It will be found that different toads have slightly different voices, and the same one can vary the tone considerably, so that it is not so easy after all to distinguish the many batrachian solos and choruses on a spring or summer evening. It will be noticed that the toad does not open its mouth when it sings, but, instead, the resonator or vocal sac under its mouth and throat is greatly expanded. One must be careful to distinguish the expansion of the mouth in breathing from the expansion of the vocal sac. See the left hand toad in the drawing (Fig. 111) for the vocal sac, and the toad in hibernation (Fig. 121) for the expansion of the mouth in breathing. It is only the males that possess the vocal sac, so that the toad chorus is composed solely of male voices.

The eggs are laid in long strings or ropes which are nearly always tangled and wound round the water plants or sticks on the bottom of the pond. If the pond is large and deep, the eggs are laid near the shore where the water is shallow. If the eggs have been freshly laid in clear water the egg ropes will look like glass tubes containing a string of jet black beads. After a rain the eggs are obscured by the fine mud that settles on the transparent jelly surrounding them, but the jelly is much more evident than in the freshly laid egg strings.

Secure enough of the egg string to include 50 or 100 eggs and place it in a glass fruit dish or a basin with clean water from the pond where the eggs were found. Let the children look at the eggs very carefully and note the color and the exact shape. Let them see whether the color is the same on all sides. If the eggs are newly laid they will be nearly perfect spheres.

Frogs, salamanders and tree toads lay their eggs in the same places and at about the same time as the toad we are to study. Only the toad lays its eggs in strings, so one can be sure he has the right kind. The others lay their eggs in bunches or singly on the plants, so they never need be mistaken for the ones sought.

The eggs which are taken to the school house for study should be kept in a light place; an east, south or west window is best.