OLFACTORY REACTIONS IN AMPHIBIANS 639 



metamorphose. Some of the larvae had one, others both pairs 

 of appendages well developed, and a few specimens passed 

 through the final phases after having been brought into the 

 laboratory. They were kept in shallow vessels with some of the 

 bottom detritus from their original habitat. Experimentation 

 and natural causes gradually diminished the numbers available 

 for the trials, but the tadpoles appeared to be normal in their 

 activities at all times. The tadpoles surviving through the period 

 of experimentation were killed by accident in the month of 

 January following. 



The second set were tadpoles taken in May of the following 

 year in the vicinity of Cambridge. They did not lend them- 

 selves well to experimentation. Conditions appeared to be 

 unfavorable for them in the laboratory. Experiments therefore 

 were carried on with but small numbers, but so far as these went 

 they were corroborative of those from the first set. 



The tadpoles included in the third set, were taken in June, 

 1913, from two different localities: namely, Cambridge and 

 Woods Hole, Massachusetts. The tadpoles were experimented 

 with particularly to show that the olfactory reactions might be 

 completely checked by a certain procedure and then revived. 



2. Methods 



The method of procedure in the trials was as follows: The 

 tadpoles were placed in filtered water for twenty-four to forty- 

 eight hours before experimentation began. Then the food was 

 introduced into the vessel; the reactions being noted in accord- 

 ance with the shifting of the food placed in the vessel. 



Food used in the tests consisted of particles of fish, earthworm, 

 or meat in decomposition. At first the food without any envelope 

 was placed free in the vessel, but later it was wrapped in cloth. 

 In other trials again, two packets were placed in the water; one 

 containing the food, the other without it. 



Very little difficulty was experienced in noting the reactions 

 of the tadpoles. When the two packets were presented, the 

 tadpoles distinguished quickly the one containing the food. 



