11. 



Bass 



:<oh 



»aOH 



CaCOH)., 



s* 



Ba(0H) 2 



VH4OH 



Length of 

 life In days 



81 



5 



30 



li 



1/6 



Aeld 



H»0 3 



HC1 



H 2 S0 4 



H3PO4 



CH3COOH 



Length of 

 lifo in days 



I* 



2- 



5 



8 



T 



As the table* show, the toxicity of SH^OH is altogether out of proportion to 

 lta etrength as a base. For this reason, is t w e specific toxicities of the 

 various iona was not within the scop* of the investigation, it was decided to 

 use only the ssetallic bases and mineral adds. 



Tables 1 and 2, experiment I, and 3 and 4, experiment II, give 

 the regeneration of individual tadpoleo la KOH and Ca(OH) 3 reepeotively. 

 The curves of growth are shorn in figures 2, 3, and 4* These experiments were 

 oarrled out in finger bowls, eaon containing two tadpoles (one of each sise) 

 in the amount of base indicated in the table Bads up to 200 e.c. with distilled 

 water. Tho solution* *ere changed dully throughout the experiment. In plott: 

 the curves, tho per cent regenerated (taxing the acount removed as 100J&) warn 

 ussd instead of the actual length rsganerated, because as Zeleny (191?) has 

 shown, •within wide limits tne length regenerated in the tail of an amphibian 

 larva is directly proportional to the length removed." 



The large range of lew ooncer.tr it iona was used to see if there 

 might be any acceleration to regeneration by low concentrators, sucm as was 

 found for development of sea urchin eggs by Loeb (1398) and Moore, Roaf, and 

 thitley (1905). Aa t«»e growth curves show, no suoh acceleration appeared. In 

 fact, the Edition of bases produces no appreciable effect until 15 o.c. have 

 been added, giving a •0075 normal base in which concentration a marked retarda- 

 tion of rago jn appears in both the KOH and Ca(0H)2« 



