THEORIES AND CONCLUSIONS 



but the result qf myriad complex chemical 

 affinities of later date? 



"Past tendencies must fade somewhat 

 as the new ones are added, and as each 

 individual has ancestors in untold numbers, 

 and as each is bound to the other like the 

 numerous threads of a fabric, individuals 

 within a species, by thus having very numer- 

 ous similar lines of heredity, are very much 

 alike ; yet no two are just alike. Cross two 

 species and see what the results will be: 

 Sharp mutations and variations appear, not 

 in the first generation, as the two are bound 

 together in a mutual compact, which, when 

 unloosed by the next and succeeding gen- 

 erations, will branch in every direction as 

 the myriad different lines of heredity combine 

 and press forward in various new directions. 

 A study of plants or animals belonging to 

 widely different species and even genera 

 which have been under similar environment 

 for a long time will always show a similarity 

 in many respects in the various means they 

 are compelled to adopt for defense in the 

 preservation and reproduction of life. Desert 

 plants often have thorns, acrid qualities and 



349 



