582 voegtlin: role of vitamines in nutrition 



great importance from a dietary point of view, as we shall see 

 later. 



In closing this chapter I should like to raise one more ques- 

 tion, namely: Do vitamines occur in colloidal form? Although 

 this question is of a highly technical nature, I do not feel that 

 I can omit giving it some consideration. I have already stated 

 that certain adsorbing agents, such as charcoal, kaolin, and mas- 

 tic, remove the vitamines from autolyzed yeast solutions, as well 

 as milk. Now we know that these reagents remove substances 

 by means of adsorption, a physico-chemical process character- 

 ized by a particular property of the surface of some finely divided 

 substances to condense on it other substances of a similar nature. 

 In order that such a condensation can take place, the adsorbing 

 as well as the adsorbed substance must be in the colloidal state. 

 We have, therefore, good reason to assume that vitamines may 

 occur in the colloidal state. If this should be proven beyond 

 doubt by future investigations, it certainly would help in explain- 

 ing the remarkable physiological action of vitamines. 



PHYSIOLOGICAL ACTION OF VITAMINES 



As to the physiological action of vitamines, but very little is 

 known at the present time. Of course, we can easily demon- 

 strate the relief of the paralytic symptoms of polyneuritis in birds 

 by means of vitamines, but we know very little as to the physio- 

 logical mechanism by which the symptoms are removed. Any- 

 body who has ever observed the effect of an active preparation 

 of vitamine on a completely paralyzed pigeon must be impressed 

 by the marvelous action of these preparations. The animals 

 may look as if on the verge of death, exhibiting a complete 

 paralysis of the voluntary muscles, accompanied with a deep 

 and abnormally slow respiration and a weakened heart action, 

 yet the injection of a few milligrams of active substance will 

 change the picture often completely within three hours. At the 

 end of this time the bird may be seen walking about normally, 

 and greedily eating the food which he had refused before the 

 treatment was initiated. To the pharmacologist the clinical 



