422 



STATE BOARD OF AGRICULTURE. 



(). Placed the sixth lot in pure liquid carbon bisulphide for a few 

 minutes. 



7. Exposed the seventh lot to carbon bisulphide vapor, over the mouth 

 of a bottle of liquid carbon bisulphide, until all the active larvae were 

 killed. All of these treatments were made between 3:00 and 5:00 P. M., 

 December 23, 1913. The results of the treatments are given in table I. 



TABLE I.— ACTIVE LARVAE OBSERVED. 



Treatment made Dec. 23, 1913. 



Dec. 31. 



1. "BlackLeaf 40" 1-272 



2. "Black Leaf 40" full strength . 



3. HgClj 1-1000 



4. Formaldehyde 1-100 



5. Formaldehyde 1-10 



6. Carbon bisulph. liquid 



7. Carbon bisulph. vapor 



Active 



Active 



None 



None 



None 



Active 



Active 



January' 2, 1914, the plates used above were all cleaned up. As the 

 only means of detecting the presence of active larvae on the plates was 

 by examining them under a microscope, it proved to be a rather difficult 

 thing to locate all of the larvae after they had crawled away from the 

 egg masses. Although the results of this experiment were not entirely 

 conclusive either for or against the theory, it was decided to continue 

 the work for the purpose of collecting data before coining to any definite 

 conclusion. 



EXPERIMENT II.— FORMALDEHYDE 1-100. 



''] 



January 7, 1914, the writer dissected out about thirty egg masses from 

 knots on Primula roots, and placed them in 1-100 solution of 40% for- 

 maldehyde for one and one-half hours, and then transferred them while 

 still wet to a plate of potato agar. The results of this treatment are 

 given in Table II. 



TABLE II.— ACTIVE LARVAE OBSERVED. 



EXPERIMENT III.— FORMALDEHYDE 1-100 AND 1-10. 



January 24, 1914, a large number of egg masses were dissected out 

 and divided into two lots. Placed the first lot in 1-100 soltuion of 40% 

 formaldehyde for ten minutes and then transferred it, while still wet, to 

 a plate of potato agar. Placed the second lot in 1-10 solution of 40% 

 formaldehyde for ten minutes and then, while still wet, transferred it to 

 a plate of potato agar. The results of this experiment are given in 

 Table III. 



