120 



Scientific Proceedings (49). 



added through the sperm, and on testing the testes of adult green 

 frogs during the breeding season, I found tyrosinase to be present, 

 although the coloration was slow to develop (72 hrs.). It is 

 possible that all of the tyrosinase in the ovary was used up in the 

 production of the egg pigment, and that the oxidase for the tad- 

 pole is introduced by the male. It is well known that oxidative 

 processes proceed much more rapidly after fertilization and perhaps 

 we may find that in other instances this is due to the entrance 

 of an oxidase with the sperm. Evidences of oxidase action have 

 been found in all of the fertilized amphibian eggs that I have 

 examined, including eggs which contain no pigment. 1 It is also 

 possible that the "poisonous complex," to which Loeb (Arch. 

 Entwick. Organ., 31, p. 658) ascribes the death of the unfertilized 

 egg, is destroyed by the entrance of an oxidase (perhaps a specific 

 oxidase) with the sperm. 



85 (694) 



On two different types of melanin. 



By BOSS AIKEN GORTNER. 



[From the Laboratory of Biological Chemistry of the Station for 

 Experimental Evolution, The Carnegie Institution of Washington.] 



In investigating the nature of the melanin molecule, I have 

 found that the pigment which is present in black wool is readily 

 soluble in dilute sodium hydroxide, and that it is apparently a 

 protein. To pigments of this nature I have given the name of 

 melano-protein to distinguish them from both the unpigmented 

 proteins and those other melanins, the nature of whose molecule 

 is as yet unknown. The melano-protein which I have obtained 

 from black wool contains no ash, showing that ash is not a part 

 of this pigment, and also proving that this melanin does not contain 

 iron. In some of the preparations of pigment from black wool 

 where less precautions were taken to insure the absence of all 

 contaminating mineral matter, a low percentage of ash was ob- 



1 In collaboration with Dr. Banta, of this station, I have recently had occasion 

 to test fertilized eggs of Rana sylvatica, Rana pipiens, Ambystoma punctalum, and 

 Spelerpes bilineatus. 



