Chapter II: Epilogue: 778

INDEX 780

LIST OF ILLUSTRATIONS

1. Nerve-cells, from larger and smaller animals (Minot, after Irving Hardesty) . . . 37

2. Relative magnitudes of some minute organisms (Zsigmondy) . . . 39

3. Curves of growth in man (Quetelet and Bowditch) . . . 61

4, 5. Mean annual increments of stature and weight in man (_do._) . . . 66, 69

6. The ratio, throughout life, of female weight to male (_do._) . . . 71

7–9. Curves of growth of child, before and after birth (His and Rüssow) . . . 74–6

10. Curve of growth of bamboo (Ostwald, after Kraus) . . . 77

11. Coefficients of variability in human stature (Boas and Wissler) . . . 80

12. Growth in weight of mouse (Wolfgang Ostwald) . . . 83

13. _Do._ of silkworm (Luciani and Lo Monaco) . . . 84

14. _Do._ of tadpole (Ostwald, after Schaper) . . . 85

15. Larval eels, or _Leptocephali_, and young elver (Joh. Schmidt) . . . 86

16. Growth in length of _Spirogyra_ (Hofmeister) . . . 87

17. Pulsations of growth in _Crocus_ (Bose) . . . 88

18. Relative growth of brain, heart and body of man (Quetelet) . . . 90

19. Ratio of stature to span of arms (_do._) . . . 94

20. Rates of growth near the tip of a bean-root (Sachs) . . . 96

21, 22. The weight-length ratio of the plaice, and its annual periodic changes . . . 99, 100

23. Variability of tail-forceps in earwigs (Bateson) . . . 104

24. Variability of body-length in plaice . . . 105

25. Rate of growth in plants in relation to temperature (Sachs) . . . 109

26. _Do._ in maize, observed (Köppen), and calculated curves . . . 112

27. _Do._ in roots of peas (Miss I. Leitch) . . . 113

28, 29. Rate of growth of frog in relation to temperature (Jenkinson, after O. Hertwig), and calculated curves of _do._ . . . 115, 6

30. Seasonal fluctuation of rate of growth in man (Daffner) . . . 119

31. _Do._ in the rate of growth of trees (C. E. Hall) . . . 120

32. Long-period fluctuation in the rate of growth of Arizona trees (A. E. Douglass) . . . 122

33, 34. The varying form of brine-shrimps (_Artemia_), in relation to salinity (Abonyi) . . . 128, 9

35–39. Curves of regenerative growth in tadpoles’ tails (M. L. Durbin) . . . 140–145

40. Relation between amount of tail removed, amount restored, and time required for restoration (M. M. Ellis) . . . 148

41. Caryokinesis in trout’s egg (Prenant, after Prof. P. Bouin) . . . 169

42–51. Diagrams of mitotic cell-division (Prof. E. B. Wilson) . . . 171–5

52. Chromosomes in course of splitting and separation (Hatschek and Flemming) . . . 180

53. Annular chromosomes of mole-cricket (Wilson, after vom Rath) . . . 181

54–56. Diagrams illustrating a hypothetic field of force in caryokinesis (Prof. W. Peddie) . . . 182–4

57. An artificial figure of caryokinesis (Leduc) . . . 186

58. A segmented egg of _Cerebratulus_ (Prenant, after Coe) . . . 189

59. Diagram of a field of force with two like poles . . . 189

60. A budding yeast-cell . . . 213

61. The roulettes of the conic sections . . . 218

62. Mode of development of an unduloid from a cylindrical tube . . . 220

63–65. Cylindrical, unduloid, nodoid and catenoid oil-globules (Plateau) . . . 222, 3

66. Diagram of the nodoid, or elastic curve . . . 224

67. Diagram of a cylinder capped by the corresponding portion of a sphere . . . 226

68. A liquid cylinder breaking up into spheres . . . 227

69. The same phenomenon in a protoplasmic cell of _Trianea_ . . . 234

70. Some phases of a splash (A. M. Worthington) . . . 235

71. A breaking wave (_do._) . . . 236

72. The calycles of some campanularian zoophytes . . . 237

73. A flagellate monad, _Distigma proteus_ (Saville Kent) . . . 246

74. _Noctiluca miliaris_, diagrammatic . . . 246

75. Various species of _Vorticella_ (Saville Kent and others) . . . 247

76. Various species of _Salpingoeca_ (_do._) . . . 248

77. Species of _Tintinnus_, _Dinobryon_ and _Codonella_ (_do._) . . . 248

78. The tube or cup of _Vaginicola_ . . . 248

79. The same of _Folliculina_ . . . 249

80. _Trachelophyllum_ (Wreszniowski) . . . 249

81. _Trichodina pediculus_ . . . 252

82. _Dinenymplia gracilis_ (Leidy) . . . 253

83. A “collar-cell” of _Codosiga_ . . . 254

84. Various species of _Lagena_ (Brady) . . . 256

85. Hanging drops, to illustrate the unduloid form (C. R. Darling) . . . 257

86. Diagram of a fluted cylinder . . . 260

87. _Nodosaria scalaris_ (Brady) . . . 262

88. Fluted and pleated gonangia of certain Campanularians (Allman) . . . 262

89. Various species of _Nodosaria_, _Sagrina_ and _Rheophax_ (Brady) . . . 263

90. _Trypanosoma tineae_ and _Spirochaeta anodontae_, to shew undulating membranes (Minchin and Fantham) . . . 266

91. Some species of _Trichomastix_ and _Trichomonas_ (Kofoid) . . . 267

92. _Herpetomonas_ assuming the undulatory membrane of a Trypanosome (D. L. Mackinnon) . . . 268

93. Diagram of a human blood-corpuscle . . . 271

94. Sperm-cells of decapod crustacea, _Inachus_ and _Galathea_ (Koltzoff) . . . 273

95. The same, in saline solutions of varying density (_do._) . . . 274

96. A sperm-cell of _Dromia_ (_do._) . . . 275

97. Chondriosomes in cells of kidney and pancreas (Barratt and Mathews) . . . 285

98. Adsorptive concentration of potassium salts in various plant-cells (Macallum) . . . 290

99–101. Equilibrium of surface-tension in a floating drop . . . 294, 5

102. Plateau’s “bourrelet” in plant-cells; diagrammatic (Berthold) . . . 298

103. Parenchyma of maize, shewing the same phenomenon . . . 298

104, 5. Diagrams of the partition-wall between two soap-bubbles . . . 299, 300

106. Diagram of a partition in a conical cell . . . 300

107. Chains of cells in _Nostoc_, _Anabaena_ and other low algae . . . 300

108. Diagram of a symmetrically divided soap-bubble . . . 301

109. Arrangement of partitions in dividing spores of _Pellia_ (Campbell) . . . 302

110. Cells of _Dictyota_ (Reinke) . . . 303

111, 2. Terminal and other cells of _Chara_, and young antheridium of _do._ . . . 303

113. Diagram of cell-walls and partitions under various conditions of tension . . . 304

114, 5. The partition-surfaces of three interconnected bubbles . . . 307, 8

116. Diagram of four interconnected cells or bubbles . . . 309

117. Various configurations of four cells in a frog’s egg (Rauber) . . . 311

118. Another diagram of two conjoined soap-bubbles . . . 313

119. A froth of bubbles, shewing its outer or “epidermal” layer . . . 314

120. A tetrahedron, or tetrahedral system, shewing its centre of symmetry . . . 317

121. A group of hexagonal cells (Bonanni) . . . 319

122, 3. Artificial cellular tissues (Leduc) . . . 320

124. Epidermis of _Girardia_ (Goebel) . . . 321

125. Soap-froth, and the same under compression (Rhumbler) . . . 322

126. Epidermal cells of _Elodea canadensis_ (Berthold) . . . 322

127. _Lithostrotion Martini_ (Nicholson) . . . 325

128. _Cyathophyllum hexagonum_ (Nicholson, after Zittel) . . . 325

129. _Arachnophyllum pentagonum_ (Nicholson) . . . 326

130. _Heliolites_ (Woods) . . . 326

131. Confluent septa in _Thamnastraea_ and _Comoseris_ (Nicholson, after Zittel) . . . 327

132. Geometrical construction of a bee’s cell . . . 330

133. Stellate cells in the pith of a rush; diagrammatic . . . 335

134. Diagram of soap-films formed in a cubical wire skeleton (Plateau) . . . 337

135. Polar furrows in systems of four soap-bubbles (Robert) . . . 341

136–8. Diagrams illustrating the division of a cube by partitions of minimal area . . . 347–50

139. Cells from hairs of _Sphacelaria_ (Berthold) . . . 351

140. The bisection of an isosceles triangle by minimal partitions . . . 353

141. The similar partitioning of spheroidal and conical cells . . . 353

142. S-shaped partitions from cells of algae and mosses (Reinke and others) . . . 355

143. Diagrammatic explanation of the S-shaped partitions . . . 356

144. Development of _Erythrotrichia_ (Berthold) . . . 359

145. Periclinal, anticlinal and radial partitioning of a quadrant . . . 359

146. Construction for the minimal partitioning of a quadrant . . . 361

147. Another diagram of anticlinal and periclinal partitions . . . 362

148. Mode of segmentation of an artificially flattened frog’s egg (Roux) . . . 363

149. The bisection, by minimal partitions, of a prism of small angle . . . 364

150. Comparative diagram of the various modes of bisection of a prismatic sector . . . 365

151. Diagram of the further growth of the two halves of a quadrantal cell . . . 367

152. Diagram of the origin of an epidermic layer of cells . . . 370

153. A discoidal cell dividing into octants . . . 371

154. A germinating spore of _Riccia_ (after Campbell), to shew the manner of space-partitioning in the cellular tissue . . . 372

155, 6. Theoretical arrangement of successive partitions in a discoidal cell . . . 373

157. Sections of a moss-embryo (Kienitz-Gerloff) . . . 374

158. Various possible arrangements of partitions in groups of four to eight cells . . . 375

159. Three modes of partitioning in a system of six cells . . . 376

160, 1. Segmenting eggs of _Trochus_ (Robert), and of _Cynthia_ (Conklin) . . . 377

162. Section of the apical cone of _Salvinia_ (Pringsheim) . . . 377

163, 4. Segmenting eggs of _Pyrosoma_ (Korotneff), and of _Echinus_ (Driesch) . . . 377

165. Segmenting egg of a cephalopod (Watase) . . . 378

166, 7. Eggs segmenting under pressure: of _Echinus_ and _Nereis_ (Driesch), and of a frog (Roux) . . . 378

168. Various arrangements of a group of eight cells on the surface of a frog’s egg (Rauber) . . . 381

169. Diagram of the partitions and interfacial contacts in a system of eight cells . . . 383

170. Various modes of aggregation of eight oil-drops (Roux) . . . 384

171. Forms, or species, of _Asterolampra_ (Greville) . . . 386

172. Diagrammatic section of an alcyonarian polype . . . 387

173, 4. Sections of _Heterophyllia_ (Nicholson and Martin Duncan) . . . 388, 9

175. Diagrammatic section of a ctenophore (_Eucharis_) . . . 391

176, 7. Diagrams of the construction of a Pluteus larva . . . 392, 3

178, 9. Diagrams of the development of stomata, in _Sedum_ and in the hyacinth . . . 394

180. Various spores and pollen-grains (Berthold and others) . . . 396

181. Spore of _Anthoceros_ (Campbell) . . . 397

182, 4, 9. Diagrammatic modes of division of a cell under certain conditions of asymmetry . . . 400–5

183. Development of the embryo of _Sphagnum_ (Campbell) . . . 402

185. The gemma of a moss (_do._) . . . 403

186. The antheridium of _Riccia_ (_do._) . . . 404

187. Section of growing shoot of _Selaginella_, diagrammatic . . . 404

188. An embryo of _Jungermannia_ (Kienitz-Gerloff) . . . 404

190. Development of the sporangium of _Osmunda_ (Bower) . . . 406

191. Embryos of _Phascum_ and of _Adiantum_ (Kienitz-Gerloff) . . . 408

192. A section of _Girardia_ (Goebel) . . . 408

193. An antheridium of _Pteris_ (Strasburger) . . . 409

194. Spicules of _Siphonogorgia_ and _Anthogorgia_ (Studer) . . . 413

195–7. Calcospherites, deposited in white of egg (Harting) . . . 421, 2

198. Sections of the shell of _Mya_ (Carpenter) . . . 422

199. Concretions, or spicules, artificially deposited in cartilage (Harting) . . . 423

200. Further illustrations of alcyonarian spicules: _Eunicea_ (Studer) . . . 424

201–3. Associated, aggregated and composite calcospherites (Harting) . . . 425, 6

204. Harting’s “conostats” . . . 427

205. Liesegang’s rings (Leduc) . . . 428

206. Relay-crystals of common salt (Bowman) . . . 429

207. Wheel-like crystals in a colloid medium (_do._) . . . 429

208. A concentrically striated calcospherite or spherocrystal
(Harting) . . . 432

209. Otoliths of plaice, shewing “age-rings” (Wallace) . . . 432

210. Spicules, or calcospherites, of _Astrosclera_ (Lister) . . . 436

211. 2. C- and S-shaped spicules of sponges and holothurians (Sollas and Théel) . . . 442

213. An amphidisc of _Hyalonema_ . . . 442

214–7. Spicules of calcareous, tetractinellid and hexactinellid sponges, and of various holothurians (Haeckel, Schultze, Sollas and Théel) . . . 445–452

218. Diagram of a solid body confined by surface-energy to a liquid boundary-film . . . 460

219. _Astrorhiza limicola_ and _arenaria_ (Brady) . . . 464

220. A nuclear “_reticulum plasmatique_” (Carnoy) . . . 468

221. A spherical radiolarian, _Aulonia hexagona_ (Haeckel) . . . 469

222. _Actinomma arcadophorum_ (_do._) . . . 469

223. _Ethmosphaera conosiphonia_ (_do._) . . . 470

224. Portions of shells of _Cenosphaera favosa_ and _vesparia_ (_do._) . . . 470

225. _Aulastrum triceros_ (_do._) . . . 471

226. Part of the skeleton of _Cannorhaphis_ (_do._) . . . 472

227. A Nassellarian skeleton, _Callimitra carolotae_ (_do._) . . . 472

228, 9. Portions of _Dictyocha stapedia_ (_do._) . . . 474

230. Diagram to illustrate the conformation of _Callimitra_ . . . 476

231. Skeletons of various radiolarians (Haeckel) . . . 479

232. Diagrammatic structure of the skeleton of _Dorataspis_ (_do._) . . . 481

233, 4. _Phatnaspis cristata_ (Haeckel), and a diagram of the same . . . 483

235. _Phractaspis prototypus_ (Haeckel) . . . 484

236. Annular and spiral thickenings in the walls of plant-cells . . . 488

237. A radiograph of the shell of _Nautilus_ (Green and Gardiner) . . . 494

238. A spiral foraminifer, _Globigerina_ (Brady) . . . 495

239–42. Diagrams to illustrate the development or growth of a logarithmic spiral . . . 407–501

243. A helicoid and a scorpioid cyme . . . 502

244. An Archimedean spiral . . . 503

245–7. More diagrams of the development of a logarithmic spiral . . . 505, 6

248–57. Various diagrams illustrating the mathematical theory of gnomons . . . 508–13

258. A shell of _Haliotis_, to shew how each increment of the shell constitutes a gnomon to the preexisting structure . . . 514

259, 60. Spiral foraminifera, _Pulvinulina_ and _Cristellaria_, to illustrate the same principle . . . 514, 5

261. Another diagram of a logarithmic spiral . . . 517

262. A diagram of the logarithmic spiral of _Nautilus_ (Moseley) . . . 519

263, 4. Opercula of _Turbo_ and of _Nerita_ (Moseley) . . . 521, 2

265. A section of the shell of _Melo ethiopicus_ . . . 525

266. Shells of _Harpa_ and _Dolium_, to illustrate generating curves and gene . . . 526

267. D’Orbigny’s Helicometer . . . 529

268. Section of a nautiloid shell, to shew the “protoconch” . . . 531

269–73. Diagrams of logarithmic spirals, of various angles . . . 532–5

274, 6, 7. Constructions for determining the angle of a logarithmic spiral . . . 537, 8

275. An ammonite, to shew its corrugated surface pattern . . . 537

278–80. Illustrations of the “angle of retardation” . . . 542–4

281. A shell of _Macroscaphites_, to shew change of curvature . . . 550

282. Construction for determining the length of the coiled spire . . . 551

283. Section of the shell of _Triton corrugatus_ (Woodward) . . . 554

284. _Lamellaria perspicua_ and _Sigaretus haliotoides_ (_do._) . . . 555

285, 6. Sections of the shells of _Terebra maculata_ and _Trochus niloticus_ . . . 559, 60

287–9. Diagrams illustrating the lines of growth on a lamellibranch shell . . . 563–5

290. _Caprinella adversa_ (Woodward) . . . 567

291. Section of the shell of _Productus_ (Woods) . . . 567

292. The “skeletal loop” of _Terebratula_ (_do._) . . . 568

293, 4. The spiral arms of _Spirifer_ and of _Atrypa_ (_do._) . . . 569

295–7. Shells of _Cleodora_, _Hyalaea_ and other pteropods (Boas) . . . 570, 1

298, 9. Coordinate diagrams of the shell-outline in certain pteropods . . . 572, 3

300. Development of the shell of _Hyalaea tridentata_ (Tesch) . . . 573

301. Pteropod shells, of _Cleodora_ and _Hyalaea_, viewed from the side (Boas) . . . 575

302, 3. Diagrams of septa in a conical shell . . . 579

304. A section of _Nautilus_, shewing the logarithmic spirals of the septa to which the shell-spiral is the evolute . . . 581

305. Cast of the interior of the shell of _Nautilus_, to shew the contours of the septa at their junction with the shell-wall . . . 582

306. _Ammonites Sowerbyi_, to shew septal outlines (Zittel, after Steinmann and Döderlein) . . . 584

307. Suture-line of _Pinacoceras_ (Zittel, after Hauer) . . . 584

308. Shells of _Hastigerina_, to shew the “mouth” (Brady) . . . 588

309. _Nummulina antiquior_ (V. von Möller) . . . 591

310. _Cornuspira foliacea_ and _Operculina complanata_ (Brady) . . . 594

311. _Miliolina pulchella_ and _linnaeana_ (Brady) . . . 596

312, 3. _Cyclammina cancellata_ (_do._), and diagrammatic figure of the same . . . 596, 7

314. _Orbulina universa_ (Brady) . . . 598

315. _Cristellaria reniformis_ (_do._) . . . 600

316. _Discorbina bertheloti_ (_do._) . . . 603

317. _Textularia trochus_ and _concava_ (_do._) . . . 604

318. Diagrammatic figure of a ram’s horns (Sir V. Brooke) . . . 615

319. Head of an Arabian wild goat (Sclater) . . . 616

320. Head of _Ovis Ammon_, shewing St Venant’s curves . . . 621

321. St Venant’s diagram of a triangular prism under torsion (Thomson and Tait) . . . 623

322. Diagram of the same phenomenon in a ram’s horn . . . 623

323. Antlers of a Swedish elk (Lönnberg) . . . 629

324. Head and antlers of _Cervus duvauceli_ (Lydekker) . . . 630

325, 6. Diagrams of spiral phyllotaxis (P. G. Tait) . . . 644, 5

327. Further diagrams of phyllotaxis, to shew how various spiral appearances may arise out of one and the same angular leaf-divergence . . . 648

328. Diagrammatic outlines of various sea-urchins . . . 664

329, 30. Diagrams of the angle of branching in blood-vessels (Hess) . . . 667, 8

331, 2. Diagrams illustrating the flexure of a beam . . . 674, 8

333. An example of the mode of arrangement of bast-fibres in a plant-stem (Schwendener) . . . 680

334. Section of the head of a femur, to shew its trabecular structure (Schäfer, after Robinson) . . . 681

335. Comparative diagrams of a crane-head and the head of a femur (Culmann and H. Meyer) . . . 682

336. Diagram of stress-lines in the human foot (Sir D. MacAlister, after H. Meyer) . . . 684

337. Trabecular structure of the _os calcis_ (_do._) . . . 685

338. Diagram of shearing-stress in a loaded pillar . . . 686

339. Diagrams of tied arch, and bowstring girder (Fidler) . . . 693

340, 1. Diagrams of a bridge: shewing proposed span, the corresponding stress-diagram and reciprocal plan of construction (_do._) . . . 696

342. A loaded bracket and its reciprocal construction-diagram (Culmann) . . . 697

343, 4. A cantilever bridge, with its reciprocal diagrams (Fidler) . . . 698

345. A two-armed cantilever of the Forth Bridge (_do._) . . . 700

346. A two-armed cantilever with load distributed over two pier-heads, as in the quadrupedal skeleton . . . 700

347–9. Stress-diagrams. or diagrams of bending moments, in the backbones of the horse, of a Dinosaur, and of _Titanotherium_ . . . 701–4

350. The skeleton of _Stegosaurus_ . . . 707

351. Bending-moments in a beam with fixed ends, to illustrate the mechanics of chevron-bones . . . 709

352, 3. Coordinate diagrams of a circle, and its deformation into an ellipse . . . 729

354. Comparison, by means of Cartesian coordinates, of the cannon-bones of various ruminant animals . . . 729

355, 6. Logarithmic coordinates, and the circle of Fig. 352 inscribed therein . . . 729, 31

357, 8. Diagrams of oblique and radial coordinates . . . 731

359. Lanceolate, ovate and cordate leaves, compared by the help of radial coordinates . . . 732

360. A leaf of _Begonia daedalea_ . . . 733

361. A network of logarithmic spiral coordinates . . . 735

362, 3. Feet of ox, sheep and giraffe, compared by means of Cartesian coordinates . . . 738, 40

364, 6. “Proportional diagrams” of human physiognomy (Albert Dürer) . . . 740, 2

365. Median and lateral toes of a tapir, compared by means of rectangular and oblique coordinates . . . 741

367, 8. A comparison of the copepods _Oithona_ and _Sapphirina_ . . . 742

369. The carapaces of certain crabs, _Geryon_, _Corystes_ and others, compared by means of rectilinear and curvilinear coordinates . . . 744

370. A comparison of certain amphipods, _Harpinia_, _Stegocephalus_ and _Hyperia_ . . . 746

371. The calycles of certain campanularian zoophytes, inscribed in corresponding Cartesian networks . . . 747

372. The calycles of certain species of _Aglaophenia_, similarly compared by means of curvilinear coordinates . . . 748

373, 4. The fishes _Argyropelecus_ and _Sternoptyx_, compared by means of rectangular and oblique coordinate systems . . . 748

375, 6. _Scarus_ and _Pomacanthus_, similarly compared by means of rectangular and coaxial systems . . . 749

377–80. A comparison of the fishes _Polyprion_, _Pseudopriacanthus_, _Scorpaena_ and _Antigonia_ . . . 750

381, 2. A similar comparison of _Diodon_ and _Orthagoriscus_ . . . 751

383. The same of various crocodiles: _C. porosus_, _C. americanus_ and _Notosuchus terrestris_ . . . 753

384. The pelvic girdles of _Stegosaurus_ and _Camptosaurus_ . . . 754

385, 6. The shoulder-girdles of _Cryptocleidus_ and of _Ichthyosaurus_ . . . 755

387. The skulls of _Dimorphodon_ and of _Pteranodon_ . . . 756

388–92. The pelves of _Archaeopteryx_ and of _Apatornis_ compared, and a method illustrated whereby intermediate configurations may be found by interpolation (G. Heilmann) . . . 757–9

393. The same pelves, together with three of the intermediate or interpolated forms . . . 760

394, 5. Comparison of the skulls of two extinct rhinoceroses, _Hyrachyus_ and _Aceratherium_ (Osborn) . . . 761

396. Occipital views of various extinct rhinoceroses (_do._) . . . 762

397–400. Comparison with each other, and with the skull of _Hyrachyus_, of the skulls of _Titanotherium_, tapir, horse and rabbit . . . 763, 4

401, 2. Coordinate diagrams of the skulls of _Eohippus_ and of _Equus_, with various actual and hypothetical intermediate types (Heilmann) . . . 765–7

403. A comparison of various human scapulae (Dwight) . . . 769

404. A human skull, inscribed in Cartesian coordinates . . . 770

405. The same coordinates on a new projection, adapted to the skull of the chimpanzee . . . 770

406. Chimpanzee’s skull, inscribed in the network of Fig. 405 . . . 771

407, 8. Corresponding diagrams of a baboon’s skull, and of a dog’s . . . 771, 3

“Cum formarum naturalium et corporalium esse non consistat nisi in unione ad materiam, ejusdem agentis esse videtur eas producere cujus est materiam transmutare. Secundo, quia cum hujusmodi formae non excedant virtutem et ordinem et facultatem principiorum agentium in natura, nulla videtur necessitas eorum originem in principia reducere altiora.” Aquinas, _De Pot. Q._ iii, a, 11. (Quoted in _Brit. Assoc. Address_, _Section D_, 1911.)

“...I would that all other natural phenomena might similarly be deduced from mechanical principles. For many things move me to suspect that everything depends upon certain forces, in virtue of which the particles of bodies, through forces not yet understood, are either impelled together so as to cohere in regular figures, or are repelled and recede from one another.” Newton, in Preface to the _Principia_. (Quoted by Mr W. Spottiswoode, _Brit. Assoc. Presidential Address_, 1878.)

“When Science shall have subjected all natural phenomena to the laws of Theoretical Mechanics, when she shall be able to predict the result of every combination as unerringly as Hamilton predicted conical refraction, or Adams revealed to us the existence of Neptune,—that we cannot say. That day may never come, and it is certainly far in the dim future. We may not anticipate it, we may not even call it possible. But none the less are we bound to look to that day, and to labour for it as the crowning triumph of Science:—when Theoretical Mechanics shall be recognised as the key to every physical enigma, the chart for every traveller through the dark Infinite of Nature.” J. H. Jellett, in _Brit. Assoc. Address_, _Section A_, 1874.

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