86 The American Naturalist. [January, 



Water plants, with the varying characteristics in proportion to their 

 growth on land or in water, were referred to, rather as hereditary powers 

 of adaptation than as acquired ones. Carnivorous plants and parasitic 

 plants were referred to in the same connection. 



Professor Meehan urged, however, that there were very strong facts 

 in favor of fortuitous variation, as there must necessarily be, to draw 

 so strong a support of that view from eminent men. A comparison of 

 some trees of the Rocky Mountains with identical species on the 

 Pacific was made. They undoubtedly had a common origin within 

 comparatively recent times, and the elevation following the upheaval 

 of the Rockies, was assumed to be the fortuitous circumstance in- 

 fluencing the change. Some of these had wandered so far apart as to 

 be regarded in some cases as distinct species. The hardiness of mag- 

 nolias, sweet gums and others, from Northern seed, as against seeds of 

 Southern trees, was also touched on. On the other hand, annual plants 

 would not resist frost. The same white frost killed foliage in these as 

 probably did long ages ago. 



Heredity was then taken up and the point made that, no matter how 

 originating, all variation was hereditary when once introduced. In 

 this respect there was no difference between what was recognized as a 

 good species or a mere variety. 



Concluding, he said : "To my mind it would be unjust to ignore the 

 separate existence of either fortuitous or definite variations. We 

 have not the remotest conception how either of these forces operate on 

 protoplasm. They may eventually be found but varied manifestations 

 of the same power ; but while we are arguing as we are to-day, arguing 

 on the separate nature of these two forces, we must concede consider- 

 able power to both, with by far the larger influence, to my mind, to 

 definite variation." 



Invertebrate Animals.— Professor McMurrich followed with the 

 discussion of the question with reference to invertebrate animals. He 

 compared the question not inaptly to the rolling of a spheroidal body 

 having a larger number of facets over a hard surface. If the ball was 

 uniformly balanced it was a matter of "chance" that is to say, of a 

 large number of causes which could not be determined or analyzed as 

 to which facet it would stop at. If, however, the ball was weighted it 

 would stop definitely on a single facet, or one close to the one selected. 



"At present," he said, "there are no extensive observations recorded 

 on the question under discussion, although there are certain special 

 cases which seem to bear more or less directly upon it. The most 



