REMOVAL OF NASAL PITS AMBLYSTOMA EMBRYOS 



35 



TABLE 1 



Reactions to moving sand grains 



CONDITION OF LARVAE 



Normal, 5 months. 

 Normal, 6 months. 

 Noseless, 5 months 

 Noseless, 6 months 



EEACriON 



20 



11 



39 



NO REACTION 



20 

 29 

 15 



PER CENT 

 POSITIVE 



50 

 27.5 

 71.7 

 50 . 



It is quite evident then, that larvae, whether normal or oper- 

 ated, will snap at almost any object which in any way simulates 

 the movements of the food, no matter whether it stimulates the 

 olfactory sense or merely the visual. An interesting fact was 

 noted in connection with the reaction of the noseless and normal 

 larvae to the sand grains. As will be seen in table 1, there is a 

 marked diminution in the total number of positive reactions 

 of the older larvae as compared with the younger. While the 

 number of reactions is far from sufficient to serve as a basis for 

 any definite conclusion, the difference in behavior suggests that 

 the larvae gradually adapt themselves to the new situation. 



The second problem was to determine experimentally whether 

 the olfactory sense played any part at all in the quest for food. 

 Bits of beef were placed in the bottom of aquaria containing 

 normal and operated individuals. The normal specimens would 

 soon nose out the beef and engulf it; the noseless ones never. 

 Exact records were not kept of these tests because the larvae 

 did not thrive on the beef. They would often gorge themselves, 

 much to their own detriment. 



Since entomostraca make up the bulk of their natural food, these 

 were used in a series of tests to determine the reaction to olfac- 

 tory stimulus. By careful handling with a capillary pipette, it 

 was possible to deposit individual Daphnids two or three milli- 

 meters from the head of the larvae, so that they would remain 

 motionless on the withdrawal of the pipette. Ninety-five tests 

 were performed on eight normal larvae; eighty-seven of these 

 resulted in positive reactions, a percentage of ninety-two. One 

 hundred and nineteen such tests performed on eight noseless 



