252 ANIMAL MORPHOLOGY 



up of atoms, and in the transfer from one race or species of a set of 

 morphological characteristics, we transfer likewise the corresponding 

 set of physiological characteristics. Thus, to return to poultry, we 

 find the rate of growth, the age at maturity, the egg-production, 

 the brooding instinct, and the resistance to disease, to be characteris- 

 tics of various races, and it is quite possible to combine such charac- 

 teristics in so far as they are not incompatible in various ways. 

 Thus. we have poultry that mature early, lay many eggs, and are not 

 broody of these the white Leghorn is a good example. Or, we may 

 have poultry that grow large, mature late, lay throughout the winter, 

 and are very broody such are the Cochins. This similarity in 

 capacity for making combinations which we see between physio- 

 logical and morphological characteristics proves their close kinship 

 and the unscientific nature of the division which would relegate their 

 study to distinct sciences. 



What is true of domesticated races is true also of wild species. Bio- 

 logy has suffered from the circumstance that species have been studied 

 almost exclusively from dead specimens. Attention is focusqd on 

 proportions in the dimensions of bones, on number of spines, on an- 

 tennal joints, on shell-markings, and so on, and we seem to have over- 

 looked entirely the fact that all these characters constitute only one 

 face of the shield. The structural descriptions of the systematist give 

 us a no more adequate idea of the characteristics of species than does 

 the sight of this exposition on a Sunday, when all wheels are stopped 

 and only the form, beautiful and grand as it is, remains, give us an 

 adequate idea of it. And so in the study of species we cannot under- 

 stand the form characteristics without considering also the function 

 characteristics. I may illustrate this by some studies which Miss Small- 

 wood 1 has been making at Cold Spring Harbor. She started with 

 a species of Amphipoda Talorchestia longicornis that lives on the 

 beach where it is rarely covered by the tide. After studying its form 

 and behavior for several months she investigated a second species 

 of the same family of Orchestidce, Orchestia palustris, that lives on the 

 salt marsh to the limit of the highest tides. After studying this for 

 some weeks with respect to behavior correlated with structure, she 

 has begun on still a third species of the same family, Alorchestes, 

 which is a typical aquatic organism. The instructive thing that comes 

 out of her studies is that in just the same way as these species differ 

 in structural characteristics they differ in functional characteristics, 

 and the two kinds of differences go hand in hand, and they have to 

 be studied together to be fully intelligible. 



In still another way are the dynamical and static characteristics 



1 Mabel E. Smallwood, The Beach Flea, Talorchestia longicornis, Cold Spring 

 Harbor Monographs, i, May, 1903. Compare also her paper, The Salt Marsh A mphi- 

 pod, Orchestra palustris, Cold Spring Harbor Monographs, 3, March, 1905. 



