450 



THE AMERICAN NATURALIST 



[Vol. LI 



It is probable tliat this principle of separability of 

 units of function and structure, wliicli has been discovered 

 in so many processes of the organism, will prove to be a 

 universal principle. This principle is more or less a 

 necessary consequence of the unit-cellular structure of 

 the organism ; if instead of being composed of cell units, 

 each possessing its peculiar heredity qualities, an organ- 

 ism were composed of fluid or solid masses of different 

 kinds, we can not imagine how it could split up into char- 

 acter units. Yet the cell is probably not the ultimate, or 

 least character unit, which is doubtless a chemicophysical 

 unit. This is extremely suggestive in connection with our 

 conceptions of the nature of the evolution process, for 

 the process more or less clearly resolves itself into three 

 problems, namely: (1) how do these character units arise; 

 (2) how are these character imits coordinated into harmo- 

 nious action within the organism; (3) why do these char- 

 acter units independently evolve, progress or retrogress! 



Since the word "character" is very vague, and since 

 the term "unit character" has a special and limited 

 meaning in Mendelian heredity, I propose the new term 

 "biocharacter" as a general desig-nation of the character 

 unit in the organism. 



1. Kinds of Biochaeacters Obsp:rved ix Paleontology 

 Biocharacters are those characters, large and small, 

 which through the evidence afforded by ontogeny (i. e., 

 zoology, embryology), phylogeny {i. e., paleontology), or 

 heredity (Mendelian inheritance) are found to be separable 

 from or independent of each other as units in the proc- 

 esses of heredity, of evolution, and of individual de- 

 velopmeiit. 



Paleontoluoy o-ivc- ,-vi.l<Mic.. no ],...itive than em- 

 brvologv ;iiid t'xiuM iiiH'iitnl ]nM i'(lit\' tluit cncli organism is 

 made up of n nmnlM-r ..f su<h s..pMral.l(' .-iiaract(M-s, inclnd- 

 iim- thoM. known a^ the "nnit .-hara.'t.'r^ " .>r Ah-ndelian 

 luTcditv. In ].alrontnl(,ov tU\< s.^i.nrabilitv in liere.litv 

 and ovohition is found to api)ly to structur.-'il. or anatom- 

 ical, characters of three ]>rincipal kinds, namelv, T, II, III: 



