EXPERIMENT STATION BULLETINS. 429 



In all of those experiments with tubes of media, the synthetic agar 

 was used. This medium gave a substratum as nearly like that of the 

 soil as could be obtained and still have it clear enough to examine un- 

 der a microscope, to determine the presence of larvae. One of the ques- 

 tions that come to mind in the use of this synthetic medium, was that of 

 the possible effect of the various salts of the medium on the chemicals 

 used in the treatments. Did not these various salts tend to act on cer- 

 tain of the chemicals so as to make them lose their power to inhibit the 

 hatching of the nematode eggs? If this occurred in the synthetic me- 

 dium, one might conceive that it also occurred in the soil and thus might 

 partially account for the failure of certain field experiments. To ob- 

 tain data on this point, it was decided to run a series of treatments on a 

 medium as free from these various nutrient salts as could be obtained. 

 The best medium that could be devised for this purpose was a plain agar 

 made of distilled water stifi'ened up with 1.5% of powdered agar. A 

 number of tubes of this medium were made, using about ten c. c. to a 

 tube. 



EXPERIMENT XII. 



March 21, 1914, a large quantity of eggs was dissected from knots on 

 roots of lettuce and squash plants, and divided into twelve lots. After 

 treatment each lot was transferred to a tube of plain agar. 



1. Placed the first lot, of 3000 eggs, in liquid carbon bisulphide for 



a few minutes. 



2. Placed the second lot, of 5000 eggs, on a cover glass and inverted 



it over the mouth of a bottle of carbon bisulphide for six and 

 one-quarter hours. On removal from the bottle the egg masses 

 were found to be very dry and hard. 



3. Placed the third lot, of 4000 eggs, in 1-100 Hg CL for a few 



minutes. 



4. Placed the fourth lot, of 8000 eggs, in a 20% solution of Cu SO^ 



for a few minutes. 



5. Placed the fifth lot, of 5000 eggs, in full strength lime-sulfur 31 to 



32° B. for a few minutes. 

 G. Placed the sixth lot, of 3000 eggs, in 1-100 H^SO^ for a few 

 minutes. 



7. Placed the seventh lot, of 3000 eggs, in 1-50 HoSO^ for a few 



minutes. 



8. Placed the eighth lot, of 3000 eggs, in 1-25 HoSO^ for a few min- 



utes. 



9. Placed the ninth lot, of 3000 eggs, in full strength H.SO^ for a few 



minutes. 



10. Placed the tenth lot, of 2000 eggs, in 1-100 solution of 40% formal- 



dehyde for a few minutes. 



11. Placed the eleventh lot, of 3000 eggs, in 1-25 solution of 40% 



formaldehyde for a few minutes. 



12. Placed the twelfth lot, of 3000 eggs, in 1-10 solution of 400% 



formaldehyde for a few minutes. 



The results of this experiment are given in Table XII. 



