ON THE ORIGIN OF GENERA. m 



the probable causes of specific characters. The species of many 

 genera do exhibit a proportion of characters which are the succes- 

 sive stages of that one which j^rogresses farthest, as the species of 

 Amblystoma in the jjosition of their teeth, nostrils, form of tail, 

 and coloration ; of Hyla in form of vomerine teeth, etc. But the 

 majority of specific characters are of divergent origin — are Amor- 

 phic " as distinguished from developmental. 



e. O71 Metaphysical Species. 



One of the arguments employed against the developmental 

 hypothesis, in any form, is that that inherent "potentiality," 

 which causes that like shall always produce like, is a metaphysi- 

 cal being, which can not be transformed, and which holds the 

 structure which it vivifies as a material expression or stamp of it- 

 self, and which therefore can not be changed. 



One expression of this inherent metaphysical specific individu- 

 ality, if the term may be allowed, has been said to be the peculiar 

 traits of the intelligence of species, their motions, voices, and in- 

 stincts. But intelligence of all animals is susceptible of impres- 

 sions, the lower the intelligence the less susceptible, and the more 

 automatic. But, as we rise in the scale of animal being, this im- 

 pressibility and capacity for education is undeniably exhibited by 

 the dog, horse, and all the well-known domesticated companions 

 of man. There can, in view of the capacities of Aves and Mam- 

 malia in these respects, be little doubt that all animals are edu- 

 cated by the " logic of events," that their intelligence, impressed 

 by changed circumstances, can accommodate itself more or less to 

 them, and that there is nothing in this part of their being opposed 

 to the principle of "descent with modification." 



There is another difficulty in. the way of accepting metaphys- 

 ical peculiarity or progenitiveness as isolating species. It is 

 marked often strongly in races or varieties, which no one pre- 

 tends to have had distinct origin. Here like produces like con- 

 tinually, though not persistently, but sufficiently to show that it 

 resides in varieties of common origin. The isolation of allied 

 species in fact depends, I believe, solely on the supremacy of the 

 automatic over the intelligent spirit. "When the intelligent rises 

 above the bounds of nature, or the automatic, the mixture or 

 separation of allied species depends merely on circumstances of 

 necessity, determined by that intelligence. 



But the metaphysical " potentiality " loses all basis, if the law 



