364 Toxicity of Dilute Solutions of Phenolic CompoundslApn\-]u\y. 



lings] is without any noticeable effect upon either the embryos or 

 larvae of Spelerpes or Amhlystoma. 



Experiments wiTH TANNIN (Commercial). Tannin inhibits 

 oxidase action and it was hoped that low conc. of tannin might 

 prove less toxic than either orcinol or resorcinol, and still inhibit 

 the formation of pigment. We have found, however, that tannin 

 in as low a conc. as 0.0125 percent kills Spelerpes eggs and embryos 

 within 24 hr. The dead eggs are more or less swollen, depending 

 on the conc. of the tannin sol. used; and when eggs in cleavage 

 stages were used, the cells of the dead eggs were sharply outlined 

 by being pulled apart f rom each other. This is probably an edemic 

 condition. 



Experiments with pyrocatechin mono-methyl ester 

 (Guaiacol). Sol. of guaiacol of 0.1-0.005 percent conc. were 

 tested on developing eggs of Rana sylvatica, Amhlystoma pundatum, 

 and Spelerpes hilineatiis. The higher conc. killed the eggs within a 

 very few hr. Using sol. of 0.005 percent conc, all of the different 

 species of eggs developed slowly for 10-15 days, but eventually 

 died before hatching. The toxic effect is best observed by the ex- 

 treme retardation of development. In conc. of 0.025 per cent or 

 greater the inner membrane of the Amhlystoma eggs is colored a 

 bright pink. 



Experiments with /^-HYDROXY-PHENYL-a-AMiNO propionic 

 ACiD (Tyrosin). Mathews (1909) and King (1912) have tested 

 the effect of a saturated sol. of tyrosin on developing eggs of Ar- 

 bacia and Chaetopterus. They found that tyrosin caused a marked 

 retardation of development but that no specific abnormalities were 

 produced. In weaker sol. than Saturation, Mathews observed in 

 some cases a slight acceleration of the general development, but in 

 most cases either no change f rom the normal or a slight retardation. 

 Tyrosin is so slightly soluble (i part in 2454 parts of water) that a 

 high conc. cannot be tested. In a saturated sol. we have noted an 

 apparent toxicity, but this is at most only slight. It seems possible 

 that a large part of this toxicity may be due to the presence of bac- 

 teria in the sol., for tyrosin sol. seemed to be very favorable for the 

 growth of bacteria. In some instances jars containing eggs and 

 tyrosin sol. have become infected with bacteria to such a degree 



