2 4 o PIONEERS OF EWLUTION PART 



plants will be choked and perish. . So in conduct. 

 For the common weal, in which the unit shares, 

 thus blending the selfish and the unselfish motives, 

 men check their natural impulses. The emotions and 

 affections which they share with the lower social 

 animals (' these/ as Huxley says, ' sometimes curiously 

 foreshadowing human policy '), only in higher degree, 

 are co-operative, and largely help the development of 

 family, tribal, and national life. But once let these 

 be weakened, and society becomes a bear-garden. 

 Force being the dominant factor in life, the struggle 

 for existence revives in all its primitive violence, 

 and atavism asserts its power. Therefore, although 

 he do the best that in him lies, man can only 

 set limits to that struggle, for the ethical process 

 is an integral part of the cosmic powers, 'just as 

 the " governor " in a steam-engine is part of the 

 mechanism of the engine/ As with society, so with 

 its units : there is no truce in the contest. Dr. 

 Plimmer, an eminent bacteriologist, describes the 

 action of a kind of yeast upon a species of Daphnia, 

 or water -flea. Metschnikoff observed that these 

 yeast-cells, which enter with the animal's food, pene- 

 trate the intestines, and get into the tissues. They 

 are there seized upon by the leukocytes, which gather 

 round the invaders in laager fashion, as if seemingly 

 endowed with consciousness, so marvellous is the 

 strategy. If they win, the Daphnia recovers ; if they 

 lose, it dies. * In a similar manner in ourselves 

 certain leukocytes (phagocytes) accumulate at any 

 point of invasion, and pick up the living bacteria ' ; 

 in the success or failure of their attack lies the fate 

 of man, and time is on the side of the bacteria. For 



