1 5 8 ANIMAL LIFE 



inorganic sources. It is just among such plastic, chame- 

 leonic Flagellates that we can trace that remote con- 

 nection between animals and plants to which biology 

 points from whatever side we study it — in infusions 

 an animal, in water a plant ; producing starch like 

 a leaf, and yet such starch as only the muscles of 

 animals evolve. Still for long intervals like an alga, 

 and anon swarming" in a dense throng like a shoal 

 of microscopic fish ; abandoned in turn by the botanists 

 to zoologists, and by zoologists to the botanists, this 

 group of J anuses is ever enticing the naturalist to its 

 study, and yet refusing to fit into the categories he has 

 made. From such Flagellates all the families of sea- 

 weeds trace their descent, as to the founder of 

 dynasties, and to them also many of the lowest animals 

 and the sponges owe their genesis. 



The loss of green pigment amongst animals would 

 thus seem to be due to their mode of feeding upon 

 organic food, which was not only a richer diet, but, 

 unlike the primitive plant food, could be obtained in 

 dark as well as in light places. 



When the activity of these dual organisms increased, 

 as it necessarily did in pursuit of fresh stores of 

 organic debris, the need for nourishment increased 

 also. The new and characteristic animal tissue — 

 muscle — demanded both oxygen for contraction and 

 also nourishment by appropriate food, and im- 

 pressed into its service that faculty for vivifying the 

 body with oxygen which in its green youth was 

 associated witli the bodv colour ; and in the lower 



