EXPERIMENT STATION BULLETINS. 



431 



pear that the longer exposure to the carbon bisulphide vapor was the 

 only cause of this difference. It was observed, however, that the egg 

 masses dipped in liquid carbon bisulphide, and those exposed to the 

 vapor for one hour did not become dried out as did those exposed to the 

 vapor for sixteen and one-half hours. This observation caused us to 

 raise the question as to what effect the loss of water might have on the 

 results. 



EXPERIMENT XIV. 



March 24, 1914, dissected out a quantity of egg masses from knots on 

 lettuce roots and placed them in a culture slide. The slide was then 

 placed on the window sill at room temperature and left there until the 

 next day. March 25, 1914, after eighteen and one-half hours of such ex- 

 posure, the egg masses which had dried down to small, hard lumps, were 

 transferred to a tube of synthetic agar. The results of this experiment 

 are given in Table XIV. 



TABLE XIV.— ACTIVE LARVAE OBSERVED. 



As the egg masses had no surface disinfection, they were not free 

 from viable fungus spores, so by March 31, 1914, the surface of the me- 

 dium was so over-run by fungi that the egg masses could no longer be 

 distinctly seen. The result of this experiment is the same as that of 

 the long exposure to carbon bisulphide vapor; so it would appear that 

 the drying which the egg masses underwent in the vapor treatment, 

 might have had some inhibitory effect. 



In looking over the data on some of the earlier experiments, it was 

 observed that in many cases the writer had subjected the egg masses to 

 the chemicals for longer periods of time than in the later experiments. 

 It was thought that this longer exposure, ten to thirty minutes, might 

 have caused the difference in results. To test this point it was decided 

 to run a series of treatments in which the egg masses should be exposed 

 for thirty minutes or more to the chemical used, before being transferred 

 to the tubes of agar. 



EXPERIMENT XV. 



March 30, 1914, a large number of egg masses were dissected from 

 knots on squash and tomato roots and divided into seven lots. After 

 treatment, each lot was transferred to a tube of synthetic agar. 



1. Placed the first lot, of 5000 eggs, in 31-32° B. lime-sulfur for 



thirty minutes. 



2. Placed the second lot, of 5000 eggs, in full strength ''Black Leaf 



40" for thirty minutes. 



3. Placed the third lot, of 3000 eggs, in 1-100 solution of 40% formal- 



dehyde for forty-five minutes. 



