218 CAREY P. McCORD AND FLOYD P. ALLEN 



was extracted with alcohol and the residue and extractives 

 respectively extracted 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 com- 

 pletely dissolved in acetone. The typical pigment cycle was 

 induced by this extract while the residue and all acetone ex- 

 tracts of muscle tissues induced no pigment changes. The resi- 

 due from acetone extraction was, however, capable of inducing 

 the growth stimulating action that McCord has described for 

 the pineal gland, while the acetone extracts which were exquisitely 

 active in inducing pigment alterations were only slightly active 

 in stimulating rapid growth. The inference is that at least 

 two separate distinct principles exist in the pineal, the one 

 producing the pigment phenomena, the other stimulating rapid 

 growth. In the case of the alcoholic extraction the active sub- 

 stances were not readily soluble, for the alcoholic extractives, 

 the alcoholic residue, and the acetone reextractives, all yielded 

 positive pigment results. The acetone extractives yielded quite 

 readily to aqueous emulsifying and this form proved to be the 

 most convenient mode of employing this material. 



Quantitative relations in time and amount of contraction 



In the feeding of pineal materials to the tadpoles the time 

 interval necessary to establish maximum contraction of the 

 pigment cells increased as the concentration decreased. Tad- 

 poles placed in a 1 : 500 pineal emulsion were noticeably lighter 

 in five minutes and required but thirty minutes to arrive at 

 maximum translucency. In higher dilutions the maximum 

 translucency was attained only after a longer interval and in 

 very high dilutions producing only qualitative changes, the 

 maximum was not attained. The dilution of 1:100,000 was the 

 highest that produced a macroscopically discernible qualita- 

 tive action. These reasonably constant quantitative relations 

 have afforded us a means for the evaluing of the strength of our 

 several preparations and may on extended study prove to be 



