Tyrosinase in Amphibian Egg Jell. 



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Certain observations on the occurrence of tyrosinase in amphibian 



egg jell. 



By A. M. Banta and Ross Aiken Gortner. 



[From the Station for Experimental Evolution, The Carnegie 

 Institution of Washington.] 



In experiments having for their object the modification of 

 pigment in amphibian larvae fresh eggs and young embryos of the 

 following species of amphibians were placed in tyrosin solutions 

 of 0.025 per cent, concentration: Ambystoma punctatum (L.), 

 Spelerpes bilineatus (Green), Bufo lentiginosus Shaw, Hyla picker- 

 ingii Holbrook, Rana clamitans Lat. and Rana sylvatica Le Conte. 



No coloration of the egg membranes or jell appeared in either 

 Ambystoma or Spelerpes. There were some indications of colora- 

 tion in Bufo jell but the coloration was so slight as to be inconclu- 

 sive. Hyla egg jell showed a pink to violet coloration within 24 

 hours, after being placed in the solution, and the solution itself 

 took on much the same color. Within 2 or 3 days the jell was 

 much blackened, and the solution was fairly dusky with suspended 

 humin. The egg jell of Rana clamitans showed some darkening 

 within a day and after forty-eight hours was conspicuously black- 

 ened while the solution was likewise very perceptibly darkened. 

 Rana sylvatica egg jell took on the rose coloration within one to 

 three hours after being placed in the solution, and the colora- 

 tion rapidly proceeded through violet to an intense black so that 

 the eggs were invisible at a depth of 3-4 cm. 



These results indicate the presence of tyrosinase in the egg 

 jell of Hyla pickeringii, Rana clamitans and Rana sylvatica, and 

 possibly in Bufo, but not in Ambystoma punctatum or Spelerpes 

 bilineatus. 



If the slight evidence of tyrosinase in Bufo is taken to indicate 

 its actual occurrence there, tyrosinase is found in the egg jell of 

 four species of Anura but is absent in the two species of Urodela 

 examined. This may possibly prove to be an additional dis- 

 tinguishing character between these two orders of amphibians. 



