20 NEW YORK STATE MUSEUM 



from nests taken from imported French stock and were al- 

 lowed to remain in a warm office at least over night. The 

 experiments detailed in series i to 4 inclusive, were performed 

 in ordinary two-quart fruit jars, healthy caterpillars being re- 

 moved from the nests and placed on blotting paper a short 

 distance from the necessarily small generators. The small 

 scale upon which the experiments were conducted rendered it 

 possible to make a large series of tests and in a relatively short 

 time. Special care was taken in the experiments detailed in 

 series 2, to prevent the exposure of the jars to direct sunlight, 

 since that undoubtedly accentuates the action of hydrocyanic 

 acid gas. The records in series 4 give the results of parallel 

 tests between glass jars exposed to ordinary light and thoise 

 kept in darkness. The caterpillars in this last series had been 

 in a warm room for over 24 hours, having been shipped from 

 Rochester January 26 and arriving in Albany the morning of 

 the 27th. 



The experiments in series 5 are particularly instructive, since 

 they were performed in a zinc lined cubical box 3 by 3 by 3 

 feet and containing 2J cubic feet. The overlapping edges were 

 carefully soldered and the removable side, its face being lined 

 with zinc, was held in place by a series of 8 bolts with thumb 

 nuts. An air-tight joint was secured by clamping the cover 

 down on to a strip of rubber y.\ inch thick and i inch wide. 

 Two drams of cyanide of potassium for each charge corre- 

 sponded very closely to i ounce for 100 cubic feet of space, 

 the slight excess probably being offset by the ^ inch rubber 

 strip adding slightly to the capacity of the box. Ten larvae 

 were placed in each of several mica lamp chimneys suspended 

 horizontally at dift'erent hights or placed in different portions 

 of the box, the .open ends being covered by coarse cheese cloth 

 held in place by elastic bands. The larvae used in experiments 

 I to 7 of this series were received early in February and kept 

 in a cool place till needed. Practically none had begun to 

 crawl and they were therefore in a hibernating condition. 

 Those employed in experiments 8 to 16 were on importations 

 received in March and had begun to leave the nests in consid- 

 erable numbers. 



A number of active caterpillars were placed in an ice box in 

 early April and kept at a low temperature for six days. These, 

 though apparently in a hibernating condition, proved no more 

 resistant to hydrocyanic acid gas fumes than active larvae. 



