266 CAUSES OF VARIATION 



bromin in the presence of water act " fatally upon all organisms 

 by splitting [the] water, forming hydro-halogen compounds, and 

 leaving the oxygen to unite with the living protoplasm." 1 



Hydrogen. Amoebae subjected to an atmosphere of hydrogen 

 for twenty-four minutes became motionless, some having assumed 

 the spherical form. The same general result followed in trades- 

 cantia hairs, but from the fact that normal activity was restored 

 by admitting air it was assumed that the results arose not from 

 any injurious effect of hydrogen but from the exclusion of oxygen. 2 



Oxids of carbon, C0 2 and CO. These two oxids of carbon 

 have very different effects upon protoplasm. The former, like 

 hydrogen, seems to act only by excluding oxygen, death, when 

 it results, being due mainly to asphyxia, while the latter kills by 

 attacking the protoplasm directly. 3 



Catalytic poisons. 4 A large number of unstable carbon com- 

 pounds, neither acid nor basic and therefore not characterized 

 by intense chemical action, are yet violent poisons. Here belong 

 the anaesthetics, as chloroform, chloral, ethyl ether, alcohols, etc. 



These unstable compounds are characterized by a " lively 

 condition of molecular movement " (Nageli), which is considered 

 to disturb the normal movements of the protoplasm, or "to 

 lead to chemical transformations in the unstable albumen of the 

 protoplasm" (Loew). 



Catalytic substances are supposed to exert their action not by 

 entering into and effecting new combinations but by disturbing, 

 through their mere presence, the usual behavior of bodies. It 

 is in this way that protoplasm suffers in their presence. Thus 

 hydrochloric and prussic acids unite only at high temperatures, 

 except in the presence of various ethers, when they will unite 

 even at 15. The vigor of this catalytic action is in proportion 

 to the molecular composition. 5 Thus in the methan series with 

 CH 3 as the base we have CH 4 , C 2 H 6 , C 3 H 8 , etc., in which 



1 C. B. Davenport, Experimental Morphology, Part I, p. 4. 

 8 Ibid. p. 5. 



3 Ibid. p. 6. 



4 A free extract from C. B, Davenport, Experimental Morphology, Part I, 

 pp. 7. 8. 



6 The facts here stated are taken almost literally from C. B. Davenport, 

 Experimental Morphology, Part I, pp. 7-8. 



