206 ALBERT M. REESE 



Experiment 12. To further test the importance of smell, using 

 that term in the usual sense, in securing food, four animals 

 were selected. It was found by dissecting preserved specimens 

 that, by inserting the points of a fine pair of scissors into the 

 two posterior nares, and cutting the intervening tissues, both 

 olfactory nerves could be sectioned with one quick cut. With 

 the four selected animals this was done, after administering 

 just enough ether to keep them from struggling. 



In three of the animals there was apparently no bleeding, 

 but in the fourth the scissors failed to work properly, and there 

 was considerable loss of blood. This animal was somewhat 

 slower in recovering its activity and was found dead in the 

 aquarium at the end of the second day. So far as observed, 

 however, its reaction to food and acid were about the same 

 as in the other three. These three recovered from the ether in 

 a few minutes and the morning after the operation they were 

 as active as ever, and gave no indication of being any the worse 

 for the operation. Once or twice a day for more than a week 

 they were tested with a bit of raw meat, but in no case attempted 

 to seize it. Two of the animals paid no attention whatever- 

 to the meat, while the third, on two or three occasions, followed 

 the meat (and also a piece of filter paper) without snapping at 

 it. Juice from raw meat and from earthworms, described above 

 caused no reaction whatever, though samples of both caused 

 the snapping response in normal animals. 



After having been without food for about two weeks the 

 animals, stimulated by extreme hunger, began to snap at meat 

 or filter paper that was moved near them. If permitted to do 

 so they would swallow the filter paper as readily as the meat. 

 They would not seize either meat or paper unless it was in motion. 



While it is hard to understand why, if sight be the sense used, 

 cutting the olfactory nerves should make an animal less apt to 

 follow a bit of meat or a tasteless piece of paper, the absolute 

 refusal of these animals to eat, after severance of the olfactory 

 nerves, seems to show that the olfactory sense is the one mainly 

 used by Diemyctylus in recognizing food. 



For two or three days after the operation, the response to a 

 .5% solution of acetic acid on the head was slower than in the 

 normal animals; but after that time the negative reaction was 

 apparently as quick and as decided as in animals with uncut 



