1914] Ross Alken Gortner and Arthur M. Banta 367 



III. SUMMARY OF GENERAL CONCLUSIONS 



1. Amphibian eggs and embryos are killed by a 0.05 percent sol. 

 of " trikresoV within ^2 hr. A sol. of o.oi percent conc. kills wood 

 frog embryos within a few days but Salamander eggs withstand 

 this amount of the drug for some time, although the development 

 is much retarded. 



2. Orcinol, in 0.05-0.01 percent conc, is fairly toxic. Young 

 amphibian embryos are killed within 10-12 days, while older em- 

 bryos may withstand 14-18 days treatment. Treatment for 6 days 

 or more produces retardation in growth, and a considerable Inhibi- 

 tion in pigment development. With the longer or stronger treat- 

 ments, especially with the younger embryos, very abnormal types 

 are produced, many of which are edemic. Certain oxidation (?) 

 products of orcinol, produced by the action of light, have many 

 times the toxicity of orcinol. 



3. Resorcinol is slightly more toxic than orcinol. It has a simi- 

 lar effect upon the course of development. With the material used 

 it is more effective than orcinol as an Inhibitor of pigmentation. 

 While, in general, resorcinol produces the same types of abnormal- 

 ities, they are more extreme and occur in a larger percentage of cases 

 than with orcinol. 



4. Pyrocatechin, pyrogallol, ol- and ß-naphthol, o.- and ß-naph- 

 thylamine, in conc. of 0.005 per cent, killed all frog and Spelerpes 

 embryos within 24 hr. In this conc. of pyrocatechin, Amblystoma 

 embryos developed very slowly and died within a few days. A 

 Solution of di-hydroxy stearic acid of this conc. is without noticeable 

 efifect upon Spelerpes or Amblystoma. 



5. Phloroglucinol is doubtfully toxic in dilute (0.05 per cent) 

 sol. When acted on by light the sol. becomes very toxic. 



6. Tannin kills all amphibian eggs within 24 hr. in conc. of 

 0.0125 percent. 



7. Guaiacol, in conc. greater than 0.005 percent, kills within a 

 few hours. A sol. of 0.005 percent conc. greatly retards develop- 

 ment and kills within 15 days. 



8. Tyrosin is, at most, only slightly toxic at Saturation (0.04 

 percent). Bacterial infections are very common and make the sol. 

 fairly toxic so as sometimes to slightly retard development and occa- 



