xlvi 



TABLE OF CONTENTS. 



Section 12. Serial connection in the structure of animals 

 mdely scattered upon the surface of our glohe. — Animals 

 living in difTerent parts of the world form frequently 

 series which are closely linked together, p. 43-47. 



Sf.ctiox 13. Relation between the size of animals and their 

 structure. — Though apparently of secondary impor- 

 tance, the size of animals bears a definite relation to 

 their structure, p. 47-49. 



Sec rio.v 14. Hi-lnlinn hrltceen the si:e of animals ami the 

 mediums in which they lice. — There is also a definite 

 relation between the size of animals and the mediums 

 in which they live, p. 49-50. 



Section 15. Permanencij of specific peculiarities in all or- 

 cjiini-ed hsinrjs. — Immutability of species, p. 51-56. 



Section IC. Relations hclween animals and plants and the 

 surrouniliiif/ u-orld. — There exist definite relations be- 

 tween the animals and plants, and the conditions under 

 which they live. Habits of animals, p. 57-63. 



Section 17. RclaUons of indiriduals to one another. — 

 The relations in which individual animals stand to one 

 another are well defined in nature, p. 63-6C. 



Section 18. Metamorphoses of animals. — Importance of 

 Embryology. Works upon this subject. Polypi, Aca- 

 leplis, Echiuodtnns, Classes of Radiata. Mollusks, 

 their aflinities and development. Articulata, their 

 range and alKnities. Worms, Crustacea, Insects. Ver- 

 tebrata. Embiyology furnishes standards to determine 

 the relative rank among animals. Distinction between 

 homologies and analogies. Independence of the devel- 

 opment of animals from external causes, p. 66-88. 



Section 19. Duration of life. — There is the greatest 

 diversity in the average duration of the life of ditferent 

 kinds of animals, p. 88-89. 



Section 20. Alternate generations. — There are animals 

 the successive generations of which are not iilcntical, 

 though their ditferences are circumscribed within defi- 

 nite cycles, p. 90-93. 



Section 21. Succession of animals and plants in geolog- 

 ical times. — The succession of organized beings in past 

 geological ages exhibits biological phenomena of the 

 most complicated nature, requiring an extensive ac- 

 ((uaintance with Zoology, Comparative Anatomy, and 

 Embryology, to be rightly appreciated. Works re- 

 latin" to the fossil remains of ditferent classes and of 

 difi'ereut geological periods. Difference between the 

 organic and inorganic kingdoms, p. 93-101. 

 Section 22. Location of types in past ages. — The geo- 

 graphical distribution of some types of animals was cir- 

 cumscribed within similar limits in past ages and 

 now, p. 102-103. 



Section 23. Limitation of species to particular geological 

 periods. — Not only species, but all other groups of ani- 

 mals and plants, have a definite range of duration, 

 p. 104-106. 



Section 24. Parallelism hetircen the geological succession 

 of animals and plants and their present relative standing. 

 ■ — The relative rardv of the animals now living coin- 

 cides with the order of succession of their representa- 

 tives In past ages, p. 107-112. 



Section 25. Parallelism between the geological succession 

 of animals and the embryonic growth of their licing rep- 

 rescntalices. — The changes which animals undergo 

 during their embryonic growth coincide also with the 

 order of succession of the fossils of the same types in 

 past ages, p. 112-116. 



Section 26. Prophetic types among animals. — Distinction 

 between prophetic, progressive, and synthetic types. 

 A deeper insight into these relations is indispensable, 

 in order to appreciate the succession of organized 

 beings in past times, p. 116-118. 



Section 27. Parallelism between the structural gradation 

 of animals and their embryonic growth. — The phases 

 of development of animals coincide with the ditferent 

 levels in the gradation of their respective types, p. 

 118-120. 



Section 28. Relations betiveen the structure, embryonic 

 growth, geological succession, and the geographical distri- 

 bution of animals. — The geographical distribution of 

 animals u[)on the surface of the globe bears direct rela- 

 tions to the rank, the embryonic growth, and the geo- 

 logical succession of their respective types, p. 120-122. 



Section 29. ALduat dependence of the animal and vegela- 

 hle Kiugiloms. — The animal and vegetable kingdoms 

 arc dependent upon one another, and stand in harmo- 

 nious relation, p. 122-123. 



Section 30. Parasitic animals and plants. — Various <le- 

 grees and ditferent kinds of parasitism among animals 

 and plants. Parasites do not form natural groups. 

 p. 123-127. 



Section 31. Combination in time and space of various 

 kinds of relations among animals. — There is not only a 

 striking relation between the rank of animals, their 

 embryonic growth, their geological succession, and their 

 geographical distribution, but even between organized 

 beings and some of the members of our solar system, 

 p. 127-131. 



Section 32. Recapitulation. — Bearing of the points con- 

 sidered in the preceding Sections u[)on the question of 

 the origin of organized beings. What Classification 

 should be. p. 132-136. 



