66 SENSE OF SMELL IN DOGFISH. 



Table 2. — Records from Five Dogfish with Left Nostril Occluded. 



As table 2 shows, the five dogfish with their left nostrils occluded consumed on 

 the average about the same length of time to find the bait that the normal dogfish 

 did, but they accomplished this by a predominance of right-handed movements rather 

 than by an almost equal number of right and left handed turns. Their movements 

 were essentially circular and seldom, if ever, in the form of a figure eight. 



A third series of dogfish were prepared by filling their right nostrils lightly with 

 cotton wool. As might have been expected from the results already recorded these 

 fish found the bait in about the same time as those with the left nostrils occluded, but 

 by means of left-handed movements chiefly. The records of this set are given in 

 table 3. 



Table 3. — Records from Five Dogfish with Right Nostril Occluded. 



As tables 2 and 3 show, dogfish with one occluded nostril each tend to seek their 

 food by moving over a more or less circular path and in such a way that the open nostril 

 is toward the center of the circle. 



Having ascertained that in seeking food or a bait normal dogfish turn about as 

 much to the right as to the left, and that those with an occluded nostril turn predomi- 

 nantly toward the side of the open nostril, I attempted as a check series to repeat all 

 the experiments thus far described on one set of fish. The plan of this series was to test 

 five dogfish, first as normal individuals, then with their left nostrils occluded, next 

 with their right nostrils occluded, and finally with both nostrils free. The fish were 

 allowed to rest one day after each trial with occluded nostrils, so that the whole series 

 of experiments covered a period of about three days. Unfortunately, during this period 

 two of the fish made their escape and the series was completed with only three fish. 

 The records of these three fish throughout the whole set of tests are given in table 4. 



