176 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



as was shown in an excellent memoir by Kammerer, 1 they 

 will change the whole histological type of their gills and 

 skin in order to meet the new functional conditions. 

 The change of the conditions of functioning is very severe 

 here, for whereas the gills had served for nutrition and 

 respiration in the uterus by a process of endosmosis 

 they now serve for respiration only, and, of course, are 

 surrounded by quite an abnormal chemical medium. 



TRUE FUNCTIONAL ADAPTATION 2 



But all other cases of morphological adaptation among 

 animals, and several in the vegetable kingdom too, belong 

 to our second group of these phenomena, which in our 

 analytical discussion we have called adaptations to functional 

 changes that result from the very nature of functioning, 

 and which we shall now call by their ordinary name, 

 " functional adaptation." 



It was Eoux who first saw the importance of this kind 

 of organic regulation and thought it well to give it a dis- 

 tinguishing name. By functioning the organisation of organic 

 tissues becomes better adapted for functioning. These words 

 describe better than any others what happens. It is well 

 known that the muscles get stronger and stronger the more 

 they are used, and that the same holds for glands, for 

 connective tissue, etc. But in these cases only quantitative 

 changes come into account. We meet with functional 

 adaptations of a much more complicated and important 



1 Arch. Entw. Meek. 17, 1904. 



2 Roux, Gesammelte Abhandlungen, vol. i. 1895 ; in particular, Der Kampf 

 der Teile im Organismus, Leipzig, 1881. 



