SS^'^oxicity of Dilute Solutions of Phenolic CompoundslA^r\\-]\x\y. 



II. EXPERIMENTAL 



Experiments with "trikresol" (Commercial). Eggs of 

 the wood frog {Rana sylvatica) and of the Salamander (Amblystoma 

 punctatum) , in early stages of development, were killed in less than 

 24 hr. when placed in a trikresol sol. stronger than 0.05 percent. The 

 eggs in 0.05 percent sol. were dead in 72 hr., without any sign of 

 further development after having been placed in the sol. The eggs 

 in O.Ol percent sol. were all alive at the end of 96 hr. and had devel- 

 oped almost as well as the control eggs, but they then gradually 

 died. At the end of a week all of the eggs with the exception of 

 two Salamander eggs were dead. These live eggs were at the blas- 

 topore stage while the check eggs were in the neural groove. No 

 further development occurred. When a sol. of 0.005 percent conc. 

 was used, all frog eggs were dead at 7 days, while the Salamander 

 eggs were only slightly retarded. The development of the Sala- 

 mander embryos continued but slightly behind the control material 

 for 41 days, at which time the larvae had been hatched for a week, 

 These larvae were normal but somewhat smaller than those in the 

 control. 



When eggs of the Salamander, Spelerpes hilineatus, were tested 

 it was found that the retardation of development was much the same 

 as for Amblystoma. Spelerpes eggs lived in o.oi percent trikresol 

 for 14 days, at which time they showed traces of pigment. The 

 control series was at this time deeply pigmented. 



Experiments with 3-5-Di-HYDROXY toluene (Orcinol). 

 Orcinol inhibits the action of tyrosinase upon tyrosin in vitro and we 

 hoped to be able to inhibit, or at least to modify the course of, pig- 

 ment development by rearing larvae in sol. of orcinol. Considerable 

 work was done with eggs and embryos of the frogs, Rana sylvatica 

 and Hyla pickeringii, the Salamander, Amblystoma punctatum, and 

 other amphibian eggs and larvae, before it was noted that the ex- 

 posure of orcinol sol. to light caused a great increase in its toxicity. 

 As a result all of the eggs and larvae were very soon killed. When, 

 however, the sol. is kept in a dimly lighted room, and when fresh 

 sol. is placed on the eggs at least three times a week, it is possible in 

 large measure to diminish the toxicity. 



The only materials which we have studied on a large scale, since 



