CHAPTER II 

 THE MECHANISM OF THE PROCESS OF DEATH. 



IN studying Laminaria it is found that toxic sub- 

 stances may be divided into two classes according to 

 their effects upon the conductivity of the tissue. The 

 first class includes those which cause a progressive loss 

 of resistance, ending in death ;* the second class produces 

 a rise in resistance, 2 followed by a fall which continues 

 until the death point is reached. 



The first group includes salts of monovalent metals. 3 

 The investigations of Eaber (1920) have shown that the 

 higher the valency of the anion (which is combined with 

 the monovalent kation) the more rapid is the fall 

 in resistance. 4 



In subsequent studies 5 it was found that the trivalent 

 arsenate anion is more efficient than the bivalent molyb- 

 date and sulphate and these in turn are more efficient 

 than the univalent formate and chlorate. 16 Further 



1 Effects of this sort are also produced by hypo- and hypertonic solu- 

 tions, by drying, by moderate heat (e.g. 35 C), by lack of oxygen, or by 

 exposure to ordinary laboratory conditions. 



* In some cases a temporary rise is observed, due to the fact that ions 

 diffuse out of the tissue faster than they diffuse in. This is easily recog- 

 nized because it is as pronounced with dead tissue as it is with living. 

 See Osterhout (1918, D}. 



z Cf. Osterhout (1912, A). 



'This does not apply to OH, which is exceptional. 



"Raber, O. L. (1921, A). 



6 In these studies the solutions were not of the same concentration, but 

 all had the conductivity of sea water, except the molybdate, which had 

 the conductivity of 75% sea water plus 25% distilled water. Hence 

 the conclusions stated above should be taken in a qualitative rather 

 than a quantitative sense. 



40 



