PINEAL GLAND FUNCTION 



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a trustworthy method for the standardization of pineal products 

 for at the present time no method exists for testing the strength 

 of such preparations. 



The quantitative relations between concentration and time 

 will be evident from the following table. 



The maximum reaction was determined by comparison with 

 a standard consisting of several tadpoles which had been placed 

 in a 1 : 500 pineal emulsion thirty minutes prior to the beginning 

 of the experiment. The translucency thus obtained was found 

 to be the greatest possible. It served as the criterion for com- 

 parison as to the degree of depigmentation induced by pineal 

 preparations of unknown activity. In the practical standardiza- 

 tion of pineal preparations, the end reaction of greatest feasibility 

 was the comparative time intervals necessary to attain to maxi- 

 mum translucency. Such a method is obviously open to the 

 criticism that frog larvae are only obtainable for a short period 

 in the year. With Bufo Americana pigment changes were 

 found to be too trivial to be of value in standardization. Rana 

 pipiens were exquisitely responsive and amirably suited for 

 standardization purposes except in that only during the spring 

 months are they obtainable. We are now experimenting with 

 certain amphibian larval forms that may be obtained through- 

 out the year. 



We have determined that the growth stimulating principle 

 in the pineal is distinct from the principle concerned in pigment 

 changes and this on further investigation may militate against 

 this proposed means of standardization. 



