THE AMPHIBIA OF OKLAHOMA 



bag but paying it no attention and eight were still behaving as though at- 

 tempting to get food from the other bag. 



It was concluded that ( 1 ) these tadpoles were esentially unstimulated by 

 the presence of a small amount of carmine; (2) since carmine is relatively in- 

 soluble in water, this is presumptive evidence that other non-soluble sub- 

 stances might not stimulate the tadpoles, if as finely divided as was the car- 

 mine and present in equal amounts; (3) the results further suggest but do not 

 prove that chemical rather than physical influences are the more important in 

 stimulating the tadpoles. 



Experiment 3. Four finger bowls were prepared as in above experiment 

 and into each were placed ten tadpoles. The dishes were labeled A, B, C, and 

 D. The temperature in the main culture on removal of the tadpoles was 

 23° C. In each of the experimental dishes it was 22.1 ° C. Dish A was retained 

 as a control. The other dishes were treated as follows: 



B. I added a t'ery small pinch from a bouillon cube to the center of the 

 dish. Contents as given on the can were salt, hydrolyzed plant protein, beef 

 extract, sugar, rendered beef fat, spices, and flavoring. Proportions were not 

 stated. The particles dissolved completely in four minutes forming a region 

 of concentration of chemical substances in the center of the bottom of the 

 dish. 



In three minutes after this material was added the tadpoles became 

 slightly agitated moving faster than those in the control. But even when they 

 came into direct contact with the added material (whether dissolved or not) 

 showed no tendency to ingest it. 



About ten minutes after the complete disappearance of solid matter I 

 added approximately three times as much of the bouillon cube as before. 

 During its dissolution bubbles arose from it. In five minutes only a small 

 bit had not dissolved and this was surrounded by a brownish spot of concen- 

 trated bouillon. The tadpoles avoided this area but elsewhere had taken up 

 the slow random swimming of the controls. 



C. A single raisin was broken into fine pieces of approximately equal 

 size (to increase surface area) and put in the center of the bottom. In one 

 minute four tadpoles were gathered about the raisin but none were feeding 

 upon it. At two minutes, one tadpole investigated the raisin, gnawed briefly 

 but soon left. Two minutes later this was repeated. For the next ten minutes 

 a tadpole or two "investigated" the raisin from time to time in a similar 

 manner but did not ingest much of it. There was no agitation such as noted 

 in Experiment 1 and no schooling. This bowl was left undisturbed for several 

 days and eventually the tadpoles ate the raisin. 



D. A small fragment from the dried bottom of Pool A with six drietl 

 tadpoles on its surface was placed in the center of the bottom ot the dish. 

 (Species of the dried tadpoles is unknown but were probably of either some 

 or all of Hylci v. versicolor, Pseudacris strec}{eri , or Rana berlandieri. They 

 were known not to be S. hurterii or Bh\o t. amcricanus.) Within a few min- 

 utes several tadpoles were ingesting the mud but there were no mass move- 

 ments and no agitation such as caused by the fish food. None attacked the 



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