1884.] NATURAL SCIENCES OP PHILADELPHIA. 143 



over a wide extent of country, it afforded a lesson in environ- 

 ment. External circumstances may influence modification, but 

 only in a line already prepared for modification. This must 

 necessarily be so, or change would be but blind accident, whereas 

 paleontology teaches us that change has always been in regular 

 lines, and in co-ordinate directions which no accident has been 

 able to permanently turn aside. Just as in the birth of animals, 

 we find, that however powerful may be some external law of 

 nutrition, which, acting on the primary cell of the individual 

 decides the sex, yet we see that no accident has been able to 

 disturb the proportion of the sexes born, which has alwaj'S been, 

 so far as we know, nearly equal. So in the birth of species, 

 making all allowance for the operation of environment, the 

 primary plan has been in no serious way disturbed ; we have to 

 grant something to environment in the production of new forms, 

 but only as it may aid an innate power of change, ready to expend 

 itself on action as soon as the circumstances favor such develop- 

 ment — circumstances which after all have very little ability to 

 determine what direction such change shall take. 



We know that distinct forms do spring through single indi- 

 viduals from seed, and that, after battling successfully with all 

 the vicissitudes of its surroundings, a new form may succeed in 

 spreading, through the lapse of years or ages, over a considerable 

 district of country. But the idea that always and in all cases 

 species have originated in this manner, presents, occasionally, 

 difficulties which seem insurmountable. In the case of the simi- 

 larity between the flora of Japan and that of the eastern portion 

 of the United States, we have to assume the existence of a much 

 closer connection between the land over what is now the Pacific 

 Ocean, in comparatively modern times, in order to get a satisfac- 

 tory idea of the departure of the species from one central spot ; 

 and to demand a great number of years for some plants to travel 

 from one central birthplace before the land subsided, carrying 

 back species in geological time further, perhaps, than mere geo- 

 logical facts would be willing to allow. But if we can see our wa}'^ 

 to a belief that plants may change in a wide district of country 

 simultaneously in one direction, and that these changes once 

 introduced, be able to perpetuate themselves till a new birth-time 

 should arrive, we have a great advancement towards sinaplifying 

 things. 



May 27. 



Mr. J. H. Redfield in the chair. 



Twenty-three persons present. 



Mr. Henry N. Rittenhouse was elected a member. 



The following were ordered to be printed : — 



