2. PHYSIOLOGICAL ADAPTATION l 



It is but a step from morphological adaptations to 

 adaptations in physiology proper. The only difference 

 between regulations of the first type and those which occur 

 in mere functioning is, that the resulting products of the 

 regulation are of definite shape and therefore distinctly 

 visible in the first case, while they are not distinctly visible 

 as formed materials but are merely marked by changes in 

 chemical or physical composition in the latter. 



Metabolism, it must never be forgotten, is the general 

 scheme within which all the processes of life in a given 

 living organism go on ; but metabolism means nothing 

 else, at least if we use the word in its descriptive and 

 unpretentious meaning, than change in the physical or 

 chemical characteristics of the single constituents of that 

 organism. In saying this, we affirm nothing about the 

 physical or chemical nature of the actual processes leading to 

 those physical or chemical characteristics, and by no means 



1 General literature : Frohlich, Das natiirlichc Zweekmassiykeitsprincip 

 in seiner Bedeutung fur Krankheit und Hciluny, 1894. Driesch, Die 

 orcjanischen Regulationen, 1901. A. Tschermak, "Das Anpassungsproblem in 

 der Physiologic der Gegenwart," iu a collection of papers in honour of J. P. 

 Pawlow, St. Petersburg, 1904. Bieganski, " Ueber die Zweckmassigkeit in den 

 pathologischen Erscheinungen," Annal. d. NaturphiL 5, 1906. Among the 

 general text-books of physiology those by Pfeffer (Pftanzenphysiologie, 1897- 

 1904) and von Bunge (Lehrbuch d. Phys. d. Menschen, 1901) are the fullest on 

 the subject of " regulations." See also different papers on general pathology 

 by Ribbert. 



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