THE EVOLUTION OF ORGANIC FORM. 81 



forms. It is constantly in action, from the germ up to maturity. 

 There is as fierce a battle between germs as between grown animals 

 as to which shall survive. The ill-adapted embryo perishes ; the well- 

 adapted lives. Of the multitudes of young, only those survive which 

 are best fitted to obtain food and escape peril. There is thus a suc- 

 cession of conditions to which the growing form must be successively 

 adapted, and each mature form is the sole survivor of a myriad of 

 germs which started together in the race of life. It has been sharply 

 selected out as the best adapted. 



The law of adaptation thus works vigorously throughout all em- 

 bryonic development. It woi'ks as decisively on matui-e forms. They 

 must be closely adapted to certain conditions of nature ; but the pos- 

 sible vai'iation in conditions is almost boundless. Not only in time 

 have there been constant changes in natural conditions, and not only 

 do they now widely vary in different localities, but even in the same 

 locality a great variety of differing conditions simultaneously exist. 



As the simple atoms of the chemical elements unite to form com- 

 plex compounds, so do simple conditions unite into complex. Numer- 

 ous sets of minor conditions exist together, from whose combination 

 are formed less numerous major conditions, and from these again a 

 single highest condition which includes all below its level. Thus each 

 locality may possess its many sets of simpler forms, and sets of 

 superior forms narrowing in number as they become adapted to a 

 wider environment, until a highest or most complex form is reached, 

 which is in physical harmony with the totality of existing conditions. 



And the question of superiority and inferiority between animals is 

 simply a question of the greater or lesser complexity of the conditions 

 to which they are fitted, the broader or narrower field of adaptation 

 which they occupy. 



But, in this quick pressing of new forms into every nook and 

 cranny of nature, there are certain general principles which have a 

 controlling influence over the resulting changes in form. One con- 

 sideration must always be taken into account, that of the character 

 of organic material of protoplasm and the forms it naturally tends 

 to assume. And a second consideration is that of the main end of 

 animal life the absorption of aliment. From this latter it follows 

 that the basic type of animal form is the stomach ; and in viewing 

 the field of animal development we behold only a series of stomachs, 

 provided with various food-taking and danger-escaping appendages. 



Evolution, then, means the gaining of superior powers of provid- 

 ing for the needs of this voracious core of all animals, the stomach ; 

 and of superior powers of escaping the voraciousness of other armed 

 and perambulatory stomachs. 



The aliment on which organisms subsist is of three kinds mineral, 

 vegetable, and animal. The pursuit of these yields two distinct classes 

 of organisms. Mineral food needs to undergo a high degree of chemi- 



TOL. XVIII. 6 



