190 THE AMERICAN NATURALIST [Vol. XLII 



ciple of the origin of species. I am told that the direct 

 effect of environment in modifying germ characters can 

 not be proven, and I retort, neither can it he disproven. 

 Paleontologists almost universally, and taxonomists gen- 

 erally, are Lamarckians, that is, those who deal chiefly 

 with range and distribution, time and space; laboratory 

 biologists, on the other hand, are almost invariably op- 

 posed to the theory of the transmissibility of acquired 

 characters. We can see no alternative hypothesis that 

 will meet the requirements of the classificationist or the 

 paleontologist, and we respectfully submit that the ex- 

 periments of a few years or even scores of years are trivial 

 in comparison with the natural experiments that go on 

 through tens of thousands of years in the origin and fix- 

 ation of species. From my little water-garden some years 

 ago I took some plants of the common water hyacinth and 

 planted them in the ground. I was surprised to find that 

 they grew luxuriantly, but that they did not develop the 

 peculiar bladder-like swelling of the leaf stems; when I 

 again transferred some small offshoots to the water, they 

 promptly redeveloped them. The plants immediately 

 changed their structure in adaptation to their terrestrial 

 or aquatic environments, and doubtless they would do 

 so after many years of isolation. But had the water 

 hyacinth been cultivated as a garden plant in the soil 

 since the time of Pliny I believe that the terrestrial char- 

 acter would have become fixed, and, after all, two or three 

 thousand years is a very short time in the history of plant 

 species. The Weismannians have been compelled to 

 recede a long way from their first position of the absolute 

 and eternal distinction between germ-plasm and body- 

 plasm; perhaps we shall yet find an intermediate place 

 that will satisfy us all. 



In claiming a high degree of importance for physio- 

 logical characters and physiological isolation in the for- 

 mation and preservation of species I need not say that 

 the term physiological is merely a confession of ignorance. 

 All physiological function must inevitably depend ulti- 



