408 PROCEEDINGS OF THE ACADEMY OF [May, 



took water and food in the normal way and then they were left undis- 

 turbed during the night. The next morning they were tested again 

 with the five oils. The following table gives the average in seconds ' 

 for the five oils before and after being varnished. 



No. of Before varnishing Next morning after var- 



■specimen. (in seconds). nishing (in seconds). 



9 37 4 57 



cT46 3 54 



9 51 9 77 



9 52 6 51 



9 81 5 78 



C? 1 75 3 82 



9 81 11 64 



9 90 » 4 32 



9 93 4 39 



9 94 8 97 



9 96 6 33 



9 116 8 50 



'9H7 15 74 



9 H8 8 82 



9 H9 6 41 



Average 7.0 61.0 



Hence, the above table shows that the average for all the spiders 

 before varnishing was 7 seconds and after the operation 61 seconds, 

 thus increasing the time nine times. The thin coating of vaseline 

 on the lyriform organs affected No. 117 the least. It responded only 

 five times slower. No. 75 was affected the most. Its time was 

 increased twenty-seven times. Some of these specimens were tested 

 the second, third and ninth day after being varnished. The result 

 was a gradual decrease in time. At the fourteenth day the varnished 

 spiders had almost returned to their normal state for detecting odors. 



Now, since this yellow vaseline itself has a slight odor, three sets of 

 controls were used to determine whether the vaseline odor interfered 

 with the response to other odors. First, vaseline in little paper boxes 

 was suspended in the cases and left over night. The cases were made 

 as near air-tight as possible, so that the next morning the air inside the 

 cases was thoroughly permeated with the vaseline odor. Tests with 

 the oils were now prosecuted with the vaseline still suspended. Second, 

 a lump of vaseline was placed on the floor of the cases. The spiders 

 paid no attention to and ran over it as if it were a pebble. Third, 

 a daub of vaseline was placed on the dorsal surface of the cephalo- 

 thorax and abdomen where it could not interfere with any of the 

 lyriform organs, and where the araneads could not rub it off. Thus 

 it was ascertained that the vaseline odor did not interfere with the 



