ATOMS AND MOLECULES 93 



some anthropologists and geologists refer his appearance on the earth to an inconceivably early period — a period 

 which the mind has difficulty in grasping. 



That modifications have taken place in the organic and inorganic kingdoms, in the fulness of time, no one will 

 doubt ; but the grand fact remains, that Hving plants and animals are the direct products of ancestors, that is, of 

 living plants and living animals ; and that the offspring, in every instance, resemble their parents and prototypes. 



No one has ever seen the birth of a new plant or animal, and it goes without saying that if thousands of years 

 are required to manufacture a new genus, and, it may be, even a new species, the proofs of the said manufacture 

 are necessarily absent. The subject is straightway removed from the category of things about which the human 

 mind can reason. The matter logically becomes a fditio principii. Endless modifications through endless time 

 are required and claimed for evolution, but these conditions, as indicated, remove it from human experience, and, 

 to a large extent, even from human history. 



The modifications in the organic and inorganic kingdoms are no doubt very slow, gentle, and minute, but they 

 are not such as to break down the great and well-defined boundaries between the several orders of plants and the 

 several orders of animals. Cultivated plants and animals, if left to themselves, revert to their original types, and 

 the progeny of alHed animals, crossed in breeding, become, as a rule, barren. 



The modifications iuT^uestion, moreover, occur simultaneously in the inorganic and orgarnc Idngdoms, so that 

 there is no dislocation of the great scheme of the universe, whereby, as I have endeavoured to show, the inorganic 

 kingdom becomes at once the foster-parent, the storehouse, and the grave of everything that lives — plant and 

 animal alike. 



§ II. Atoms and Molecules Fundamental in the Inorganic and Organic Kingdoms. 



The atoms and molecules of the physical universe have always been, and still are, the atoms and molecules 

 from which plants and animals are built up, with the addition of that far-reaching and mysterious factor called 

 life. The atoms and molecules aggregate and are marshalled by life into the symmetric and asymmetric forms 

 (plant and animal) with which all biologists and physiologists are famiUar. The atoms and molecules, as already 

 explained, arrange themselves in straight lines and in spirals, and combine to form tissues bounded by straight 

 fines and plane surfaces, or by curves and spirals. The straight-line and spiral formations are met with in the 

 simplest plants and animals, as well as in the most complex. They are seen even in the spores, seeds, and eggs. 

 Eod-fike structures are not uncommon in the beginnings of fife, and spiral seeds and ova are of frequent occurrence 

 in plants and animals. The carpogonia of Chara helicteris, and the spermatozoa of the cray-fish [Astacus fluviatilis), 

 provide the necessary illustration. The egg-purses of sharks and dog-fishes also reveal beautiful spirals. The rod-fike 

 and spiral formations are not chance structures. They are the results of reproduction, growth, and development, 

 and have been going on throughout the ages. No one can, of course, say why the atoms and molecules arrange 

 themselves in the manner indicated. We must accept the arrangements as we find them in both the inorganic and 

 organic kingdoms. The arrangements are to be regarded as ultimate facts in physics, biology, and physiology. 

 There is no getting behind or beyond them. It is not possible even to imagine that the endless examples of 

 crystals, dendrites, and spiral formations and movements which we behold in the universe, and in plants and animals, 

 are the result of accident. 



The fact that crystals, dendrites, spirals, &c., are formed in unvar}ang sequence, and that plants and animals 

 reproduce themselves, and have done so for countless ages, shows that they are, and have always been, under law 

 and order. That they will so continue, while the present order of things lasts, can scarcely be doubted. 



There is no need to assume that the plants and animals of the present day materially or fundamentally differ 

 from the plants and animals of pre-historic times. That species, and even races of plants and animals, may have 

 died out, and new forms come into existence, does not destroy the argument that the atoms and molecules forming 

 the plants and animals of the present day act in precisely the same directions as they have always done. 

 Neither does it disturb the relations which exist as between the inorganic and organic atoms and molecules as a 

 whole. The mere form or external configuration of plants and animals does not destroy the fundamental relations 

 which are known to exist as between the inorganic and organic kingdoms. Great physical upheavals have, no 

 doubt, occasionally dislocated, for the time being, those fundamental relations, but out of the wreck, so to speak, 

 new races of plants and animals have arisen to supplement those which have perished ; and the new races, like 

 the old ones, have been linked to the physical universe by atomic and molecular action quite as closely as the 

 primeval plants and animals were finked to a pre-existing state of things. 



The relations between the inorganic and organic kingdoms are now, and always have been, of the most intimate 

 description ; a state of matters which compels us, when speaking of the origin, distribution, and fives of plants 

 and animals, to consider the universe as we find it. 



