On Species. 315 



tliis general notion, when irritten out in words, we may take as 

 an approximate formula of the species. One system of philoso- 

 phy thence argues that this result of induction is nothing but a 

 notion of the mind, and that species are but an imaginary pro- 

 duct of logic ; or at least, that since, as they say (we do not 

 now discuss this point), genera are groupings without definite 

 limits which may be laid off variously by different minds, so 

 species are undefined, and individuals are the onl}^ realities — the 

 supposed limits to species being regarded as proof of partial 

 study, or a consequence of a partial development of the kingdoms 

 of nature. Another system infers, on the contrary, that species 

 are realities, and the general or type idea has, in some sense, a 

 rea? existence. A third admits that species are essentially reali- 

 ties in nature, but claims that the general idea exists only as a 

 result of logical induction. 



The discussion in the preceding pages sustains most nearly the 

 la^t view, that species are realities in the system of nature while 

 manifest to us only in individuals ; that is, they are so far real, 

 that the idea for each is definite, even of mathematical strictness, 

 (although not thus precise in our limited view,) it proceeding 

 from the mathematical and finite basis of nature. They are the 

 ^nits fixed in the plan of creation ; and individuals are the ma- 

 terial expressions of those ideal units. 



At the same time, we learn, that while species are realities in a 

 post important and fundamental sense, no comprehensive type- 

 idea of a species can be represented in any material or immate- 

 rial existence. For while a species has its constants, it has also 

 its variables, each variable becoming a constant so far only as its 

 law and limits of variation are fixed; and in the organic king- 

 doms, moreover, each individual has its historic phases, from the 

 germ through the cycle of growth. The general idea sought 

 put by induction, therefore, is not made up of fnvariables. Lim- 

 ited to these, it represents no object, class of objects, or law, in 

 nature. The variables are a necessary complement to the inva- 

 riables; and the complete species-idea is present to the mind, only 

 ^hen tlie image in view is seen to be ever changing along the 

 lines of variables and development. Whatever individualized 

 conception is entertained, it is evidently & conception of the spe- 

 cies in one of its phases,— that is, under some one specific condi- 

 tion as to size, form, color, constitution, etc., as regards each part 

 in the structure, from among the many variations in all these 

 I'cspects that are possible : mind can picture to itself individ- 

 uals only and not species, and one phase at a time in the life 

 of an organic individual, not the whole cycle. 



We may attempt to reach what is called the typical form of a 

 species, in order to make this the subject of a conception. But 

 even within the closest range of what may be taken as typical 



