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Mr. J. Gray. 



magnesium citrate in water, a definite precipitate of magnesium phosphate 

 is formed. If, however, sodium phosphate and ammonia are added to a 

 solution of magnesium citrate in sodium citrate, no precipitate is formed, 

 although a considerable amount of magnesium is in solution. We may 

 conclude, therefore, that the inability of tartrate or citrate mixtures to 

 maintain the normal equilibrium, of ciliated cells may prove to be due to 

 the absence of free magnesium and calcium ions and not to the direct effect 

 of the anions. Confirmation of this view will be given later in this paper. 



As far as I am aware, the only satisfactory investigation of the effects of 

 anions on other living processes is that of Sakai (9) on the heart of the 

 frog. This author used solutions containing balanced cations, but does not 

 refer to their hydrogen ion concentration. His results may be summarised 

 as follows : — 



I', Br' 7 N(V Beat well maintained, even faster than normal. 

 CI' Normal. 



S0 4 " Beat well maintained, after initial slowing. 



Git'" Rate steadily falls and finally heart stops. 



There is clearly no fundamental difference between the effect of anions 

 on ciliary and on muscular activity. Both types of tissue are remarkably 

 indifferent to wide variations in the nature of the anions in the external 

 environment. 



(b) The Effects of Solutions of Pwie Sodium Salts. 



Whereas in a solution of a sodium salt containing K", Ca", and Mg", the 

 ciliated epithelium is remarkably indifferent to a variation in the nature 

 of the anions present, yet in a solution of a sodium salt, which does not 

 contain other cations, the tissue shows a very marked sensitivity to par- 

 ticular anions. Table II shows the general course of events. 



It will be seen that the salts can be divided into two main groups : 



A. Those salts which cause the cells to swell up by the absorption of 



water. CI' < , N0 3 ' < , Br' < , V ; 



B. Those salts which' do not cause the cells to swell. S0 4 ", Tartrate, 



Citrate ; 



while the acetate forms an intermediary type. 



It is also clear that these solutions cannot indicate the direct effect of the 

 environment on the contractile mechanism ; their effect on the cell is of a 

 more general nature, and the contractile mechanism is only secondarily 

 involved.* 



* Cilia often remain active when the process of absorbing water is relatively far 

 advanced. 



