1914] Ross Alken Gortner and Arthur M. Banta 361 



time (4-10, or more, days depending on the initial age of the em- 

 bryo), a considerable retardation in development is produced as well 

 as a great retardation of pigment production. The first pigment 

 appears in the eye to be f ollowed, a little later, by a narrow " V " on 

 the Shoulders and, a day or two later, by a narrow line down the 

 spine. This condition persists so long as the larvae remain in the 

 resorcinol sol., but the toxicity of the drug is so great that even in 

 so low a conc. as 0.0125 percent, death ensues after an immersion 

 of 15-18 days even when the sol. is changed daily. In many in- 

 stances we have had larvae in resorcinol sol. which were almost en- 

 tirely devoid of pigment, excepting for their eyes, when the control 

 animals (from the same group of eggs) were fully pigmented and 

 had the entire larval pigment pattern fully developed. 



When the larvae are removed from the sol. after varying lengths 

 of time, depending on the initial age of the embryo, we obtain two 

 distinct types of animals. The more extreme type resembles the 

 orcinol type but is heavier, the flippers are more enlarged, the pig- 

 ment reticulations are t.^o. as contrasted with the coarse reticulation 

 of the orcinol type. This type persists for 60-70 days when kept 

 in water, but since the animals do not feed, death by starvation even- 

 tually ensues. 



The second type probably represents individuals which have not 

 been so profoundly modified. The body form is practically normal, 

 but the typical pigment pattern does not develop, the pigmentation 

 being very fine and dull in color. The majority of this type also die 

 of starvation. In nearly every instance, in both the orcinol and re- 

 sorcinol series, the larvae remain, until death, much lighter in color 

 than those individuals in the control series. 



The greater number of the experiments, where eggs and embryos 

 of Rana sylvatica, Hyla pickeringii, or Amblystoma punctafum were 

 used, were carried out before we had noted the extreme toxicity 

 produced by the action of light on resorcinol sol., and are therefore 

 only records of very rapid deaths. Inasmuch as all of these eggs 

 contain pigment, the differences in pigment development could not 

 be easily foUowed. 



The eggs of Rana sylvatica and Amblystoma puncfatum, when 

 treated in the early developmental stages, produce in the larvae the 



