30 CAEEY P. McCOKD 



criterion for comparison as to the degree of depigmentation induced by 

 pineal preparations of unknown activity. In 'the practical standardization 

 of pineal preparations, the end reaction accepted was the comparative 

 time intervals necessary to attain to maximum translucency. With Bufo 

 americana, pigment changes were found to be too trivial to be of value 

 in standardization. Rana pipiens were exquisitely responsive and ad- 

 mirably suited for standardization purposes except that only during the 

 spring months are they obtainable. 



It was determined that the growth stimulating principle in the pineal 

 is distinct from the principle concerned in pigment changes and this, on 

 further investigation, more or less, may invalidate this proposed means of 

 standardization. 



Results. Making use of this method of standardization, McCord 

 and Allen sought to determine the relative activity of various split products 

 derived from the pineal gland. 



In the preparation of these split materials, the fresh glands were 

 either ground up and immediately extracted or desiccated and subse- 

 quently extracted. After numerous observations with a variety of frac- 

 tipnation methods, it was found that chief interest centers around the 

 acetone and alcohol extractives and their residues. In the case of acetone, 

 the process was carried out in a Soxhlet apparatus. On freeing the 

 extractive from acetone, there resulted a brownish black fatty mass with 

 an odor suggestive of crude fish oil. Portions of these extractives and the 

 residue were preserved intact for experimentation. Other portions of both 

 were reextr acted with alcohol. Likewise, fresh pineal material was ex- 

 tracted with alcohol, and the residue and extractives, respectively, ex- 

 tracted subsequently with acetone. These several preparations were tested, 

 as to their influence upon pigmentation, on several hundred tadpoles from 

 the same hatchings. At once it was apparent that the pigment altering 

 principle was completely dissolved in acetone. The typical pigment cycle 

 was induced by this extract, while the residue as well as all control acetone 

 extracts of muscle tissues induced no pigment changes. The residue from 

 acetone extraction was, however, capable of inducing the growth stimulat- 

 ing action described for the pineal gland, while the acetone extracts, 

 which were exquisitely active in inducing pigment alterations, were only 

 elightly active in stimulating growth. The inference is that at least 

 two distinct principles exist in the pineal, the one producing the pigment 

 phenomena, the other stimulating growth. In the case of the alcoholic 

 extraction, the active substances were not readily soluble, for the alcoholic 

 extractives, the alcoholic residue, and the acetone reextractives, all yielded 

 positive pigment results. 



