848 LIFE : OUTLINES OF GENERAL BIOLOGY 



kinds of protoplasm, originating at different times. The first kind, 

 "mycoplasm", was formed when the waters covering the earth were 

 still hot, if not near boiling-point ; it is of the nature of chromatin, 

 and is well represented in Bacteria for instance. The second kind, 

 "amoeboplasm", was formed later, and fed upon Biococci, consisting 

 of particles of mycoplasm. But some of these Biococci, ingested by 

 the primitive amoeboid units, defied digestion, and became internal 

 partners of their captors. Eventually they formed nuclei. The 

 locomotor powers of the primitive amoeboid units were abetted by 

 the ferment-making powers of the engulfed Biococci. 



THE DIVERGENCE OF PLANTS AND ANIMALS.— Linn^us 

 made a wise use of the term "Organisata'' to include both plants 

 and animals, for they stand together as organisms, in contrast to 

 things in general. Claude Bernard in his famous — and even classic — 

 essay, Phenomenes de la Vie communs aux Animaux et aux Vegetaux 

 (1878), showed how much there is in common in the vital processes 

 of the two "kingdoms". In their cellular structure, and in the indi- 

 vidual development from a fertilised egg-ceU, there is further 

 illustration of the fundamental unity of plants and animals. There 

 is a vegetative side to the most vigorous animal ; there is something 

 of the beast imprisoned in many a plant. Yet, after all, plants and 

 animals are very different. They represent different ways of attacking 

 and solving the problem of surviving and mastering; they exhibit 

 different physiological regimes, different policies. And one of the 

 early great steps in evolution must have been the divergence of 

 plants and animals. 



The contrasts between typical plant and typical animal are many 

 and obvious, but there are many simple organisms which are not 

 emphatically on either line of evolution. It is difficult to be sure 

 whether the "Flowers-of-Tan" {Fuligo varians), a pest that creeps 

 on the bark of the tanyard, should be called a plant or an animal. 

 It belongs to the class of Myxomycetes, which botanists claim as 

 "slime-fungi", and zoologists as primitive Rhizopods, which may, 

 however, be neither, yet something of both. Such organisms suggest 

 that though the genealogical tree of Organisata be somewhat 

 Y-like, there were undecided organisms for a long time before the 

 great dichotomy occurred. 



What is the fundamental contrast between plants and animals? 

 Plants are organisms that are able to obtain nutritive materials at 

 a low chemical level, able to synthetise relatively simple inorganic 

 substances — notably carbon dioxide and water. Animals are organ- 

 isms that feed at a high level, on the carbon compounds manufac- 

 tured by other creatures. It is probable that the dichotomy began 

 long before there was chlorophyll, which is now so important in 

 the photo-synthesis characteristic of green plants. The fundamentad 



