Zoological Prohlems for Natural History Society. o 



The J were wont to speak of animals having a common 

 plan of structure, and to explain that by plan they meant 

 an idea in the mind of the Creator. With the advent of 

 Darwin, all this was changed, and it was recognized that 

 the fundamental agreement in structure of many different 

 animals implied community of descent. This enlightening 

 and fascinating idea gave a tremendous spur to anatomical 

 investigation, and for a time the dissecting room and the 

 laboratory almost monopolized the attention of natural 

 history students, especially when, at the same time, 

 the new mode of interpreting the development or life 

 history of animals, as a recapitulation of the ancestral 

 history of the race, came into the foreground. 



Of late years, however, there has been somewhat of 

 a revulsion of feeling in this respect. It has been 

 remembered that an animal is not a mere piece of 

 intricately constructed matter, but a working machine, 

 and in order to properly understand it, it must be studied 

 living amidst its natural surroundings. We ought to 

 beware of repeating the mistake of the older anatomists 

 and over-emphasizing one side of the truth. We cannot, 

 it is true, fully explain the structure of an animal with 

 reference to its present habits and surroundings. If we 

 could, all evidence for the descent of different animals 

 from a common ancestor would disappear. No, an 

 animal is to be compared to a piece of wax which has 

 been passed through many different moulds, each of 

 which has left its impress, and the newer impress has 

 never entirely obliterated the traces of the older. Each 

 form-impressing mould will then represent a set of cir- 

 cumstances and of habits possessed by the ancestors of 

 the animal at one period of its existence, and the present 

 habits and environment represent, so to speak, the last 

 mould into which the piece of wax has been pressed. 



In studying the surroundings and habits, then, we are 

 not merely trying to explain some part of an animal's 



