1396.] Proceedings of Scientific Societies. 435 



New York Academy of Sciences.— Biological Section, March 

 9th.— Mr. F. B. Sumner read a paper on '« The Descent Tree of the 

 Variations of a Land Snail from the Philippines," illustrated by a 

 lantern slide. Mr. Sumner described the range in variation in size 

 and markings in the shell, and arranged the varieties in the form of a 

 tree of three branches diverging from the most generalized type. It 

 was shown that these several varieties occupy the same geographical 

 region and Mr. Sumner was of the opinion that their occurrence could 

 not be explained by natural selection since if the colorations were 

 supposed to be protective it would be impossible to explain the evolu- 

 tion of these three types. Prof, Osborn, in discussion, was inclined to 

 take the same view. Dr. Dyar, however, thought the explanation by 

 natural selection not necessarily excluded, since the variations seemed 

 analogous to the dimorphism in sphinx larvae, which has been shown 

 by Poulton to be probably due to this factor. 



The other paper was by Dr. Arnold Graf on " The Problem of the 

 Transmission of Acquired Characters." 



Dr. Graf discussed the views of the modern schools of evolutionists 

 and adopted the view that the transmission of acquired characters 

 must be admitted to occur. He cited several examples which seemed 

 to support this view, and especially discussed the sucker in leeches as 

 an adaptation to parasitism and the evolution of the chambered shell 

 in a series of fossil Cephalopoda. 



Prof. Osborn remarked in criticism of Dr. Graf's paper that this 

 statement does not appear to recognize the distinction between ontogenic 

 and phylogenic variation, or that the adult from any organism is an 

 exponent of the stirp, or constitution. The Environment. If the 

 environment is normal the adult would be normal, but if the environ- 

 ment (which includes all the atmospheric, chemical, nutritive, motor 

 and psychical circumstances under which the animal is reared) were to 

 change, the adult would change correspondingly ; and these changes 

 would be so profound that in many cases it would appear as if the 

 constitution, or stirp, had also changed. Illustrations might be given 

 of changes of the most profound character induced by changes in 

 either of the above factors of the environment, and in the case of the 

 motor factor or animal motion, the habits of the animal might, in the 

 course of a life time, profoundly modify its structure. For example, 

 if the human infant were brought up in the branches of a tree as an 

 arboreal type instead of as a terrestrial, bi-pedal type, there is little 

 doubt that some of the well known early adaptations to arboreal habit 

 (such as the turning in of the soles of the feet, and the grasping of the 



