Pharmacodynamics of Salts and Drugs hi 



the case of the ferment. This is, of course, to be expected since in the 

 egg we are deahng with a vastly more compHcated system than in the 

 ferment. We have not only a variety of ferments and substances 

 which might be differently affected by the salts, but the eggs are in 

 addition separated from the water in which the salts are by mem- 

 branes which are known to be variously permeable to different salts. 

 The fact that the results show so good an agreement with the com- 

 puted values is hence the more satisfactory. As regards the excep- 

 tions, it will be observed by comparing Figs. 3 and 4 that they are in 

 general the same in each, only the deviations are greater for the egg. 

 Thus zinc, which toward diastase was somewhat more poisonous than 

 it should be, toward the eggs is very much more toxic. Cobalt, which 

 is too little toxic toward diastase, shows the same relationship toward 

 the eggs; the same is true of mercury. On the other hand, certain 

 very interesting special exceptions occur. Thus cadmium, which 

 toward diastase occupies almost exactly its theoretical position, is 

 toward Fundiilus heteroclitus eggs extremely toxic. It is, in fact, so 

 toxic and so far out as to show that there is some specific and special 

 reason for its aberrance. I have accordingly disregarded it. On the 

 other hand, lead, which was for some special reason far out of place 

 toward diastase, is here almost where it should be. 



As regards the toxicity of the metals sodium, potassium, and 

 lithium it will be noticed that they are relatively more toxic toward 

 Fundiilus than toward the diastase. The reason for this may possibly 

 be that the strong solutions are in themselves harmful by their osmotic 

 action on the cells. 



I have also incorporated the results of a few observations made 

 upon the rapidly swimming culture of Volvox glohaior (Fig. 5). I de- 

 termined the concentration just sufficient to stop swimming within two 

 minutes. The computation of the constant a, from the results gives a 

 very satisfactory agreement. 



e) Other results on toxicity. — The results of Caldwell on bromelin, 

 the proteolytic ferment of the pineapple, I have been unable to bring 

 to any satisfactory numerical agreement. But while Caldwell's re- 

 sults cannot be brought into quantitative relationship with McGuigan's 

 and mine, the general trend of the results is plainly the same. The order 

 of the toxicity of the metals is in nearly all cases as it should theoreti- 



