EXPERIMENT STATION BULLETINS. 



587 



Apples (fruit) that Avere infested with San Jose scale, were obtained. 

 Tiny blocks of apple were cut out so that each scale would be supplied 

 with enough sap to keep her from drying up for a time. After many 

 specimens had been prepared in this way, they were divided so that 

 part of them could be kept in the air as a check and the rest could be 

 placed in containers of pure nitrogen above mercury for diiferent periods 

 of time. 



At the beginning, three or four changes of nitrogen were used with 

 the specimens until all air had passed by diffusion from the pieces of 

 apple in the containers. (A specimen of P. coniditus, placed in one 

 of the containers of nitrogen with the pieces of apple, bearing scales, 

 became motionless within ten minutes. The beetle recovered entirely 

 at the end of the experiment.) Results for the check specimens, that 

 had been kept in air, as well as for specimens confined fifteen, hours 

 and eighteen hours, respectively, in pure nitrogen are given in table X. 



TABLE X. 



San Jose Scale in nitrogen 18 hours. 



(Examined 48 hours after being removed to air.) 



Check in air 66 hours. 



7 adults 1 , 

 13 young / ^^^^ 



2 young. 



4 less than half grown. 



65 less than half grown. 

 j 19 adults. 



I 8 adults with 38 young under the scales 

 I with them. 



Son Jose Scale in nitrogen 15 hours. 

 (Examined 48 hours after being removed to air.) 



21 adults. 



81 less than half grown. 

 6 adults with 21 young with them. 



6 about half grown specimens. 



The specimens that had been kept in nitrogen* were removed and 

 then kept in air alongside of the check specimens for two days in order 

 that they might have time either to show that they were dead by 

 shriveling and turning dark), or to recover from the nitrogen if they 

 were still alive. Then they were examined. The specimens marked 

 ''doubtful" in the table had not shriveled or decayed but they would 

 not respond to the touch of a needle point. Those marked alive, showed 

 by movement that they were alive. The checks, kept in air, showed 

 that the little pieces of apple were able to furnish the necessary moist- 

 ure to keep the scales alive for the time of the experiment. Of those 



*It was interesting to note that the pieces of apple kept in nitrogen stayed almost the color of 

 freshly cut apples until they were exposed to the air at the end of the test. 



