Xo. f>(i4] 



FIXATIOX OF (.' II AHA ("TEH 



707 



particular degree of coalescence or adnation exhibited 

 between them, is of great functional importance.' Many 

 structures, insignificant and in all probability quite use- 

 less, are extremely constant throughout large group- of 

 animals and plants. Must we believe that all these con- 

 servative characters and structures are of immense 

 importance in the struggle for existence, but that >nch 

 features as size, shape, color and texture, which are com- 

 paratively inconstant, are of much less survival value? 

 It is true that certain discoveries of modern physiology 

 have lent some support to the oft-repeated defence of the 

 selection theory that structures of apparently little impor- 

 tance may be in reality of much significance to the organ 

 ism. Our knowledge of vital processes is as yet so slight 



feature as certainly! of great or of little value for survival, 

 but the mass of such information as we have acquired 

 from a study of anatomy, physiology and ecology points 

 decidedly to the conclusion that it is precisely those char- 

 acters of little importance to the organism which are 

 usually most conservative. 



It is also very doubtful if the constancy of such appar- 

 ently more essential characters as the vertebral column of 

 vertebrates, the feathery covering of birds, or the floral 

 reproduction of seed plants is due to the supreme impor- 

 tance of these characters in the struggle for existence, as 

 the selection theory postulates; for it is evidently not the 



per s/which is of great significance to the individual, but 

 the presence of these structures in very specific size, 

 shape, texture, color and other respects. The vertebral 



columns of a shark and of an elephant could not 1 x- 



changed without disaster, nor could the feather- of a 

 duck and an ostrich or the flowers of a pine and an orchid. 

 The "conservative" character is useful only as it is asso- 

 ciated in each individual with many other -variable" 



between a fern and a flowering plant resides in their 



