Chapter I: Voyage From New York to Rio De Janeiro (2)

“Next come the Chubs, or in scientific nomenclature the Cyprinoids. These fishes, variously called Chubs, Suckers, or Carps, abound in all the fresh waters of the northern hemisphere. They are also numerous in the eastern part of the southern hemisphere, but have not a single representative in South America. As the Goniodonts are characteristic of the southern hemisphere in its western half, so this group seems to be characteristic of it in its eastern half. But while the Cyprinoids have no representative in South America, there is another group there, structurally akin to them, called the Cyprinodonts. They are all small-sized; our Minnows belong to this group. From Maine to Texas they are found in all the short rivers or creeks all along the coast. It is for this reason that I expect to find the short coast rivers of South America abounding in Minnows. I remember to have found in the neighborhood of Mobile no less than six new species in the course of an afternoon’s ramble. These fishes are almost all viviparous, or at least lay their eggs in a very advanced state of development of the young. The sexes differ so greatly in appearance that they have sometimes been described as distinct species, nay, even as distinct genera.[12] We must be on our guard against a similar mistake. Here again we have two groups, the Cyprinoids and Cyprinodonts, so similar in their structural features that the development of one out of the other naturally suggests itself. But in South America there are no Cyprinoids at all, while the Cyprinodonts abound; in Europe, Asia, and North America on the contrary, the Cyprinoids are very numerous and the Cyprinodonts comparatively few.” The Characines were next considered with reference to their affinities as well as their geographical distribution; and a few remarks were added upon the smaller families known to have representatives in the fresh waters of South America, such as the Erythrinoids, the Gymnotines, &c. “I am often asked what is my chief aim in this expedition to South America? No doubt in a general way it is to collect materials for future study. But the conviction which draws me irresistibly, is that the combination of animals on this continent, where the faunæ are so characteristic and so distinct from all others, will give me the means of showing that the transmutation theory is wholly without foundation in facts.” The lecture closed with some account of the Salmonidæ, found all over the northern hemisphere, but represented in South America by the Characines, distinct species of which may be looked for in the separate water-basins of Brazil; and also of several other important families of South American fishes, especially the Osteoglossum, the Sudis, &c., interesting on account of their relation to an extinct fossil type, that of the Cœlacanths.[13]

_April 17th._—Yesterday was Easter Sunday, and the day was beautiful. The services from Bishop Potter in the morning were very interesting; the more so for us on account of the God speed he gave us. Wind and weather permitting, it is the last Sunday we shall pass on board ship together. The Bishop spoke with much earnestness and sympathy of the objects of the expedition, addressing himself especially to the young men, not only with reference to their duties as connected with a scientific undertaking, but as American citizens in a foreign country at this time of war and misapprehension.

This morning we were quite entertained at meeting a number of the so-called “Catamarans,” the crazy crafts of the fishermen, who appear to be amphibious animals on this coast. Their boats consist of a few logs lashed together, over which the water breaks at every moment without apparently disturbing the occupants in the least. They fish, walk about, sit, lie down or stand, eat, drink, and sleep, to all appearance as contented and comfortable as we are in our princely steamer. Usually they go into port at nightfall, but are occasionally driven out to sea by the wind, and may sometimes be met with two hundred miles and more from the shore. To-day we have fairly come upon the South American coast. Yesterday we could catch sight occasionally of low sand banks; but this morning we have sailed past the pretty little town of Olinda, with its convent on the hill, and the larger city of Pernambuco, whose white houses come quite down to the sea-shore. Immediately in front of the town lies the reef, which runs southward along the coast for a hundred miles and more, enclosing between itself and the shore a strip of quiet waters, forming admirable anchorage for small shipping. Before Pernambuco this channel is quite deep, and directly in front of the town there is a break in the reef forming a natural gateway through which large vessels can enter. We have now left the town behind, but the shore is still in sight; a flat coast rising into low hills behind, and here and there dotted with villages and fishing-huts.

The lecture on Saturday was rather practical than scientific, on the best modes of collecting and preserving specimens, the instruments to be used, &c. To-day it was upon the classification of fishes as illustrated by embryology; the same method of study as that explained the other day and now applied to the class of fishes. “All fishes at the time when the germ becomes distinct above the yolk have a continuous fin over the whole back, around the tail, and under the abdomen. The naked reptiles, those which have no scales, such as frogs, toads, salamanders, and the like, share in this embryological feature of the fishes. From this identity of development I believe the naked reptiles to be structurally nearer to the true fishes than to the scaly reptiles. All fishes, and indeed all Vertebrates, even the highest, have, at this early period, fissures in the side of the neck. These are the first indications of gills, an organ the basis for which exists in all Vertebrates at a certain period of their life, but is fully developed and functionally active only in the lower ones, in which it acquires a special final structure; giving place to lungs in the higher ones before they reach their adult condition. From this time forward not only the class characters, but those of the family, begin to be distinguished. I will show you to-day how we may improve the classification of fishes by studying their embryology. Take, for instance, the family of Cods in its widest acceptation. It consists of several genera, among which are the Cod proper, the Cusk, and the Brotula. Naturalists may differ in their estimation of the relative rank of these genera, and even with reference to their affinity, but the embryology of the Cod seems to me to give the natural scale. In its early condition the Cod has the continuous fin of the Brotula, next the dorsal and caudal fins become distinct, as in the Cusk, and lastly the final individualization of the fins takes place, and they break up into the three dorsals and two anals of the Cod. Thus the Brotula represents the infantile condition of the Cod, and of course stands lowest, while the Cusk has its natural position between the two. There are other genera belonging to this family, as, for instance, the Lota or fresh-water Cusk and the Hake, the relative position of which may be determined by further embryological studies. I had an opportunity of observing something in the development of the Hake which throws some light on the relation of the Ophidini to the Cod family, though thus far they have been associated with the Eel. The little embryonic Hake on which I made my investigation was about an inch and a half in length; it was much more slender and elongated in proportion to its thickness than any of the family of Cods in their adult condition, and had a continuous fin all around the body. Although the structural relations of the Eels are not fully understood, some of them, at least, now united as a distinct family under the name of Ophidini, are known to be closely connected with the Cods, and this character of the Hake in its early condition would seem to show that this type of Eel is a sort of embryonic form of the Cod family.

“Another well-known family of fishes is that of the Lophioides. To this group belongs the Lophius or Goose-fish, with which the Cottoids or Sculpins, and the Blennioids, with Zoarces and Anarrhichas, the so-called Sea-cat, ought to be associated. It was my good fortune to have an opportunity of studying the development of the Lophius, and to my surprise I found that its embryonic phases included the whole series here alluded to, thus presenting another of those natural scales on which I hope all our scientific classifications will be remodelled when we obtain a better knowledge of embryology. The Lophius in its youngest stage recalls the Tænioids, being long and compressed; next it resembles the Blennioids, and growing stouter passes through a stage like Cottus, before it assumes the depressed form of Lophius. In the family of Cyprinodonts I have observed the young of Fundulus. They are destitute of ventrals, thus showing that the genus Orestias stands lowest in its family. I would allude to one other fact of this kind observed by Professor Wyman. There has been a doubt among naturalists as to the relative standing of the Skates and Sharks. On geological evidence I had placed the Skates highest, because the Sharks precede them in time; but this fact had not been established on embryological evidence. Professor Wyman has followed the embryology of the Skate through all its phases, and has found that in its earlier condition it is slender in outline, with the appearance of a diminutive shark, and that only later it assumes the broad shield-like form and long tapering tail of the skate. Were it only that they enable us to set aside all arbitrary decisions and base our classifications on the teachings of nature, these investigations would be invaluable; but their importance is increased by the consideration that we are thus gradually led to recognize the true affinities which bind all organized beings into one great system.”

_April 20th._—The day after to-morrow we shall enter the Bay of Rio de Janeiro. One begins to see already that little disturbance in the regularity of sea life which precedes arrival. People are making up their letters, and rearranging their luggage; there is a slight stir pervading our small party of passengers and breaking up the even tenor of the uniform life we have been leading together for the last three weeks. It has been a delightful voyage, and yet, under the most charming circumstances, life at sea is a poor exchange for life on land, and we are all glad to be near our haven.

On Tuesday the lecture was upon the formation and growth of the egg; a sort of practical lesson in the study of embryology; yesterday, upon the importance of ascertaining, at the outset, the spawning season of the animals in Brazil, and the means to that end. “It will often be impossible for us to learn the breeding season of animals, a matter in which country people are generally very ignorant. But when we cannot obtain it from persons about us, there are some indications in the animals themselves which may serve as a guide. During my own investigations upon the development of the turtles, when I opened many thousands of eggs, I found that in these animals, at least, the appearance of the ovaries is a pretty good guide. They always contain several sets of eggs. Those which will be laid this year are the largest; those of the following year are next in size; those of two years hence still smaller, until we come to eggs so small that it is impossible to perceive any difference between their various phases of development. But we can readily tell whether there are any eggs so advanced as to be near laying, and distinguish between the brood of the year and those which are to be hatched later. When the eggs are about to be laid the whole surface is covered with ramifying blood-vessels, and the yolk is of a very clear bright yellow. Before the egg drops from the ovary this network bursts; it shrivels up and forms a little scar on the side of the ovary. Should we, therefore, on examining the ovary of a turtle, find that these scars are fresh, we may infer that the season for laying is not over; or if we find some of the eggs much larger than the rest and nearly mature, we shall know that it is about to begin. How far this will hold good with respect to alligators and other animals I do not know. I have learned to recognize these signs in the turtles from my long study of their embryology. With fishes it could hardly be possible to distinguish the different sets of eggs because they lay such numbers, and they are all so small. But if we cannot distinguish the eggs of the different years, it will be something to learn the size of their broods, which differs very greatly in different families.”

The lecture concluded with some advice as to observing and recording the metamorphoses of insects. “Though much has been written on the societies of ants and other like communities in Brazil, the accounts of different naturalists do not agree. It would be well to collect the larvæ of a great many insects, and try to raise them; but as this will be difficult and often impossible in travelling, we must at least get the nests of ants, bees, wasps, and the like, in order to ascertain all we can respecting their communities. When these are not too large it is easy to secure them by slipping a bag over them, thus taking the whole settlement captive. It may then be preserved by dipping into alcohol, and examined at leisure, so as to ascertain the number and nature of the individuals contained in it, and learn something at least of their habits. Nor let us neglect the domestic establishments of spiders. There is an immense variety of spiders in South America, and a great difference in their webs. It would be well to preserve these on sheets of paper, to make drawings of them, and examine their threads microscopically.”

_April 21st._—Yesterday Mr. Agassiz gave his closing lecture, knowing that to-day all would be occupied with preparations for landing. He gave a little history of Steenstrup and Sars, and showed the influence their embryological investigations have had in reforming classification, and also their direct bearing upon the question of the origin of species. To these investigators science owes the discovery of the so-called “alternate generations,” in which the Hydroid, either by budding or by the breaking up of its own body, gives rise to numerous jelly-fishes; these lay eggs which produce Hydroids again, and the Hydroids renew the process as before.[14]

“These results are but recently added to the annals of science, and are not yet very extensively known in the community; but when the facts are more fully understood, they cannot fail to affect the fundamental principles of zoölogy. I have been astonished to see how little weight Darwin himself gives to this series of transformations; he hardly alludes to it, and yet it has a very direct bearing on his theory, since it shows that, however great the divergence from the starting-point in any process of development, it ever returns to the road of its normal destiny; the cycle may be wide, but the boundaries are as impassable as if it were narrower. However these processes of development may approach, or even cross each other, they never end in making any living being different from the one which gave it birth, though in reaching that point it may pass through phases resembling other animals.

“In considering these questions we should remember how slight are most of those specific differences, the origin of which gives rise to so much controversy, in comparison with the cycle of changes undergone by every individual in the course of its development. There are numerous genera, including many very closely allied species, distinguished by differences which, were it not for the fact that they have remained unchanged and invariable through ages, might be termed insignificant. Such, for instance, are the various species of corals found in the everglades of Florida, where they lived and died ages ago, and had the identical specific differences by which we distinguish their successors in the present Florida reefs. The whole science of zoölogy in its present condition is based upon the fact that these slight differences are maintained generation after generation. And yet every individual on such a coral stock,—and the same is true of any individual in any class whatsoever of the whole animal kingdom, whether Radiate, Mollusk, Articulate, or Vertebrate,—before reaching its adult condition and assuming the permanent characters which distinguish it from other species, and have never been known to vary, passes in a comparatively short period through an extraordinary transformation, the successive phases of which differ far more from each other than do the adult species. In other words, the same individual differs more from himself in successive stages of his growth than he does in his adult condition from kindred species of the same genus. The conclusion seems inevitable, that, if the slight differences which distinguish species were not inherent, and if the phases through which every individual has to pass were not the appointed means to reach that end, themselves invariable, there would be ever-recurring deviations from the normal types. Every naturalist knows that this is not the case. All the deviations known to us are monstrosities, and the occurrence of these, under disturbing influences, are to my mind only additional evidence of the fixity of species. The extreme deviations obtained in domesticity are secured, as is well known, at the expense of the typical characters, and end usually in the production of sterile individuals. All such facts seem to show that so-called varieties or breeds, far from indicating the beginning of new types, or the initiating of incipient species, only point out the range of flexibility in types which in their essence are invariable.

“In the discussion of the development theory in its present form, a great deal is said of the imperfection of the geological record. But it seems to me that, however fragmentary our knowledge of geology, its incompleteness does not invalidate certain important points in the evidence. It is well known that the crust of our earth is divided into a number of layers, all of which contain the remains of distinct populations. These different sets of inhabitants who have possessed the earth at successive periods have each a character of their own. The transmutation theory insists that they owe their origin to gradual transformations, and are not, therefore, the result of distinct creative acts. All agree, however, that we arrive at a lower stratum where no trace of life is to be found. Place it where we will: suppose that we are mistaken in thinking that we have reached the beginning of life with the lowest Cambrian deposit; suppose that the first animals preceded this epoch, and that there was an earlier epoch, to be called the Laurentian system, beside many others older still; it is nevertheless true that geology brings us down to a level at which the character of the earth’s crust made organic life impossible. At this point, wherever we place it, the origin of animals by development was impossible, because they had no ancestors. This is the true starting-point, and until we have some facts to prove that the power, whatever it was, which originated the first animals has ceased to act, I see no reason for referring the origin of life to any other cause. I grant that we have no such evidence of an active creative power as Science requires for positive demonstration of her laws, and that we cannot explain the processes which lie at the origin of life. But if the facts are insufficient on our side, they are absolutely wanting on the other. We cannot certainly consider the development theory proved, because a few naturalists think it plausible: it seems plausible only to the few, and it is demonstrated by none. I bring this subject before you now, not to urge upon you this or that theory, strong as my own convictions are. I wish only to warn you, not against the development theory itself, but against the looseness in the methods of study upon which it is based. Whatever be your ultimate opinions on this subject, let them rest on facts and not on arguments, however plausible. This is not a question to be argued, it is one to be investigated.

“As I have advanced in these talks with you, I have become more and more dissatisfied, feeling the difficulty of laying out our work without a practical familiarity with the objects themselves. But this is the inevitable position of one who is seeking the truth: till we have found it, we are more or less feeling our way. I am aware that in my lectures I have covered a far wider range of subjects than we can handle, even if every man do his very best; if we accomplish one tenth of the work I have suggested, I shall be more than satisfied with the result of the expedition. In closing, I can hardly add anything to the impressive admonitions of Bishop Potter in his parting words to us last Sunday, for which I thank him in your name and my own. But I would remind you, that, while America has recovered her political independence, while we all have that confidence in our institutions which makes us secure, that so far as we are true to them, doing what we do conscientiously and in full view of our responsibilities we shall be in the right path, we have not yet achieved our intellectual independence. There is a disposition in this country to refer all literary and scientific matters to European tribunals; to accept a man because he has obtained the award of societies abroad. An American author is often better satisfied if he publish his book in England than at home. In my opinion, every man who publishes his work on the other side of the water deprives his country of so much intellectual capital to which she has a right. Publish your results at home, and let Europe discover whether they are worth reading. Not until you are faithful to your citizenship in your intellectual as well as your political life, will you be truly upright and worthy students of nature.”

At the conclusion of these remarks a set of resolutions was read by Bishop Potter.[15] They were followed by a few little friendly speeches, all made in the most informal and cordial spirit; and so ended our course of lectures on board the Colorado. Later in the day we observed singular bright red patches in the sea. Some were not less than seven or eight feet in length, rather oblong, and the whole mass looked as red as blood. Sometimes they seemed to lie on the very top of the water, sometimes to be a little below it, so as only to tinge the rippling surface. One of the sailors succeeded in catching a portion of it in a bucket, when it was found to consist of a solid mass of little crustaceans, bright red in color. They were all very lively, keeping up a constant rapid motion. Mr. Agassiz examined them under the microscope and found them to be the young of a crab. He has no doubt that every such patch is a single brood, floating thus compactly together like spawn.

-----

Footnote 2:

On the 17th of May, nearly a month after our arrival in Rio, this
cloud was interpreted to us. It was, indeed, charged with the issues
of life and death, for it was on this day and the following that the
final assaults on Petersburg were made, and the cloud which marred an
otherwise stainless sky, as we were passing along the shores of
Virginia, was, no doubt, the mass of smoke gathered above the opposing
lines of the two armies.

Footnote 3:

The species of Hydroids most numerous upon the gulf-weed have not yet
been described, and would form a valuable addition to the Natural
History of the Acalephs. For an account of the animals of this class
inhabiting the Atlantic coast of North America, and especially the New
England shores, I may refer to the third volume of my Contributions to
the Natural History of the United States, and to the second number of
the Illustrated Catalogue of the Museum of Comparative Zoloögy at
Cambridge.—L. A.

Footnote 4:

“This stream,” he writes, “is probably generated by the great
accumulation of water on the eastern coast of America, between the
tropics, by the trade-winds which constantly blow there.” These views,
though vaguely hinted at by old Spanish navigators, were first
distinctly set forth by Franklin, and, as is stated in a recent
printed report of the Coast Survey Explorations, “they receive
confirmation from every discovery which the advance of scientific
research brings to aid in the solution of the great problem of oceanic
circulation.”

Footnote 5:

No one can read the account of the explorations undertaken by the
Coast Survey in the Gulf Stream, and continued during a number of
successive years, and the instructions received by the officers thus
employed from the Superintendent, Dr. A. D. Bache, without feeling how
comprehensive, keen, and persevering was the intellect which has long
presided over this department of our public works. The result is a
very thorough survey of the stream, especially along the coast of our
own continent, with sections giving the temperature to a great depth,
the relations of the cold and warm streaks, the form of the ocean
bottom, as well as various other details respecting the direction and
force of the current, the density and color of the water, and the
animal and vegetable productions contained in it. (See Appendix No.
I.)—L. A.

Footnote 6:

This anticipation was more than confirmed by the result of the
journey. It is true that Mr. Agassiz did not go beyond the Peruvian
frontier, and therefore could not verify his prophecy in that region.
But he found the localization of species in the Amazons circumscribed
within much narrower limits than he expected, the whole length of the
great stream, as well as its tributaries, being broken up into
numerous distinct faunæ. There can be no doubt that what is true for
nearly three thousand miles of its course is true also for the
head-waters of the Amazons; indeed, other investigators have already
described some species from its higher tributaries differing entirely
from those collected upon this expedition.

Footnote 7:

Mr. Agassiz afterward visited these hills himself, and an account of
their structure and probable origin will be found in the chapter on
the physical history of the Amazons.

Footnote 8:

See Appendix No. II.

Footnote 9:

It proved in the sequel unnecessary to seek the glacial phenomena of
tropical South America in its highest mountains. In Brazil the
moraines are as distinct and as well preserved in some of the coast
ranges on the Atlantic side, not more than twelve or fifteen hundred
feet high, as in any glaciated localities known to geologists in more
northern parts of the world. The snow line, even in those latitudes,
then descended so low that masses of ice formed above its level
actually forced their way down to the sea-coast.—L. A.

Footnote 10:

In copying the journal from which these notes are taken, I have
hesitated to burden the narrative with anatomical details. But for
those who take an interest in such investigations it may be well to
add here that the frog, when first hatched, is simply an oblong body,
without any appendages, and tapering slightly towards its posterior
end. In that condition it resembles the Cecilia. In its next stage,
that of the tadpole, when the extremity has elongated into a tail, the
gills are fairly developed, and it has one pair of imperfect legs, it
resembles the Siren, with its rudimentary limbs. In its succeeding
stages, when the same animal has two pairs of legs and a fin around
the tail, it recalls the Proteus and Menobranchus. Finally the gills
are suppressed, the animal breathes through lungs, but the tail still
remains; it then recalls Menopoma and the Salamanders. At last the
tail shrinks and disappears, and the frog is complete. This gives us a
standard by which the relative position of the leading groups of the
class may safely be determined.—L. A.

Footnote 11:

On account of the many exploring expeditions for which the Bay of Rio
de Janeiro has been a favorite port, it has acquired a special
interest for the naturalist. It may seem at first sight as if the fact
that French, English, German, Russian, and American expeditions have
followed each other in this locality, during the last century, each
bringing away its rich harvest of specimens, by diminishing its
novelty would rather lessen than increase its interest as a collecting
ground. On the contrary, for the very reason that the specimens from
which the greater part of the descriptions and figures contained in
the published accounts of these voyages were obtained from Rio de
Janeiro and its neighborhood, it becomes indispensable that every
zoölogical museum aiming at scientific accuracy and completeness
should have original specimens from that very locality for the
identification of species already described. Otherwise doubts
respecting the strict identity or specific difference of specimens
obtained on other parts of the Atlantic shore, not only in South
America but in Central and North America, may at any time invalidate
important generalizations concerning the distribution of animals in
these seas. From this point of view, the Bay of Rio de Janeiro forms a
most important centre of comparison, and it was for this reason that
we made so prolonged a stay there. Although the prospect of
discovering any novelties was diminished by the extensive
investigations of our predecessors, I well knew that whatever we
collected there would greatly increase the value of our collections
elsewhere. One of my special aims was to ascertain how far the marine
animals inhabiting the coast of Brazil to the south of Cape Frio
differed from those to the north of it, and furthermore, how the
animals found along the coast between Cape Frio and Cape St. Roque
differed from or agreed with those inhabiting the more northern shore
of the continent and the West Indian Islands. In the course of the
following chapters I shall have occasion to return, more in detail, to
this subject.—L. A.

Footnote 12:

Molinesia and Pœcilia.

Footnote 13:

This lecture was accompanied by careful descriptions and drawings on
the blackboard, showing the structural differences between these
groups. These are omitted, as they would have little interest for the
general reader. The chief object in reporting these lectures is to
show the aims which Mr. Agassiz placed before himself and his
companions in laying out the work of the expedition, and these are
made sufficiently clear without further scientific details.

Footnote 14:

As these investigations have been published with so much detail
(Steenstrup, Alternate Generation, Sars’s Fauna Norwegica; L. Agassiz,
Contr. to Nat. Hist. of U. S.), it has not been thought necessary to
reproduce this part of the lecture here. Any one who cares to read a
less technical account of these investigations than those originally
published, will find it in “Methods of Study,” by L. Agassiz.

Footnote 15:

See Appendix No. III.