THE ORIGIN AXD DEVELOPMENT OF ORGANISMS 341 



Such has been the history of animals and plants. So far as we 

 can learn of that history, it has always been one of divergence 

 from common centers, the process being repeated over and over 

 again in successive ages, until finally there has resulted the 

 great diversity of organisms that people the world of to-day. 



At the beginning of life in the world there was, apparently, 

 no difference between animals and plants. We have already 

 seen that some organisms so closely resemble both groups that 

 we cannot say whether they are animals or plants. Possibly 

 some such organisms were the first to inhabit .the world. As 

 progress continued, however, the descendants of these origi- 

 nal forms of life diverged from each other along two great 

 lines, one of which acquired the habit of living upon the 

 other. The original form of life must have been capable of 

 utilizing the mineral ingredients hi nature, possibly like the 

 green plants of to-day. Whether the original organisms were 

 capable of carrying on photosynthesis we do not know, but 

 hi some way they must have been able to utilize minerals. 

 However that may be, their descendants diverged into two 

 groups, one group acquiring the green coloring matter and the 

 power of utilizing carbon dioxid and sunlight and, by means 

 of chlorophyll, building up starch, thus giving rise to plants. 

 The second group of descendants, losing this power of utilizing 

 minerals, and acquiring the power of feeding upon the mate- 

 rials which were manufactured by the first group, developed 

 into the kingdom of animals. 



After plants and animals were thus separated and each had 

 developed for a time along its own line, some of the plants lost 

 their chlorophyll and acquired the habit of depending upon 

 other plants for food, thus becoming the Fungi. As the history 

 of the world progressed, each of the two great types thus 

 started continued to repeat the history of divergence. Age 

 after age the descendants continued to separate into different 

 lines, until the modern world was finally produced, with its 

 endless series of different forms, all having been derived from 

 common centers by descent with divergence. 



