130 GENEEAL EVOLUTIOK 



number of individuals than those which were similar in specific 

 characters. In other words, it is common to a large number of 

 species. This kind of character we call generic, and the grouping 

 it indicates is a genus. 



Farther analysis brings to light characters of organism which 

 are common to a still greater number of individuals ; this we call 

 a family character. Those which are common to still inore nu- 

 merous individuals are the ordinal: they are usually found in 

 parts of the structure which have the closest connection with the 

 whole life-history of the being. Finally, the individuals compos- 

 ing many orders will be found identical in some important char- 

 acter of the systems by which ordinary life io maintained, as in 

 the nervous and circulatory : the divisions thus outlined are called 

 classes. 



By this process of analysis we reach in our animal or plant 

 those peculiarities which are common to the whole animal or vege- 

 table kingdom, and then we have exhausted the structure so com- 

 pletely that we have nothing remaining to take into account beyond 

 the cell-structure or homogeneous protoplasm by which we know 

 that it is organic, and not a mineral. 



The history of the origin of a type, as species, genus, order, 

 etc., is simply the history of the origin of the structure or struct- 

 ures which define those groups respectively. It is nothing more 

 nor less than this, whether a man or an insect be the object of 

 investigation. 



EVIDENCES OF DEEIVATION. 



a. Of Specific Characters. 



The evidences of derivation of species from species, within the 

 limits of the genus, are abundant and conclusive. In the first 

 place, the rule which naturalists observe in defining species is a 

 clear consequence of such a state of things. It is not amount and 

 degree of difference that determine the definition of species from 

 species, but it is the permanency of the characters in all cases and 

 under all circumstances. Many species of the systems include va- 

 rieties and extremes of form, etc., which, were they at all times 

 distinct, and not connected by intermediate forms, would be esti- 

 mated as species by the same and other writers, as can be easily 

 seen by reference to their works. 



Thus, species are either "restricted " or "protean," the latter 



