EXPERIMENT STATION BULLETINS. 



425 



hibit nematode egg development, it was thought that this influence might 

 be even greater if the containing vessel were smaller and more tightly 

 sealed. To test this point, we decided to run a series of treatments in 

 culture slides instead of petri dishes. 



EXPERIMENT VII. 



March 7, 1914, dissected out a large number of egg masses from infest- 

 ed roots and divided them into eleven lots of about 3,000 eggs each. 

 After treatment each lot was transferred to a cover glass and sealed down 

 over a culture slide. 



I, 2 and 3. The first three lots were rinsed in sterile water and served 

 as checks on the treatments. 



4. Treated the fourth lot in 3% hydrogen peroxide for a short time. 



5. Treated the fifth lot in 1-100 solution of 40% formaldehyde for a 

 short time. 



6. Treated the sixth lot in 1-25 solution of 40% formaldehyde for a 

 short time. 



7. Treated the seventh lot in 1-10 solution of 40% formaldehyde for 

 a short time. 



8. Treated the eighth lot in 40% formaldehyde for a snort time. 



9. Treated the ninth lot in 1-1000 Hg 01, for a short time. 



10. Treated the tenth lot in jjure liquid carbon bisulphide for a short 

 time. 



II. Placed the eleventh lot on a cover-glass and exposed it to carbon 

 bisulphide vapor for ten minutes. 



The results of these experiments are given in table VII. 



TABLE VII.— ACTIVE LARVAE OBSERVED. 



Treatment March 7, 1914. 



1. Sterile water 



2. Sterile water 



3. Sterile water 



4. Peroxide .3% 



5. Formaldehyde 1-100. 



6. Formaldehyde 1-25.. 



7. Formaldehyde 1-10. . 



8. Formaldehyde 40%. , 



9. HgCl2 1-1000 



10. Carbon bisul. liq 



11. Carbon bisul. vapor. , 



Discontinued 

 Discontinued 

 Discontinued 

 Discontinued 

 Discontinued 

 Discontinued 

 Discontinued 

 Discontinued 



Discontinued 

 Discontinued 



With the exception of the 1-1000 Hg. CL treatment, the various chemi- 

 cals all produced more or less of an inhibitory effect on the eggs. And, 

 even where the eggs did hatch, as in the 1-100 formaldehyde and the 

 carbon bisulphide vapor treatment, the larva? soon died. From this 

 latter fact, it would appear that chemicals were still present in the sealed 

 culture slides to such an extent as to be' intolerable to the larvae. The 

 large numbers of larvae that hatched from eggs in the check slides would 

 seem to show that the chemicals were exerting a great influence. This 

 and the previous experiments with closed vessels pointed quite strongly 

 toward the surroundings as an important factor in our laboratory ex- 

 periments. 



In order to see whether the exception, in the case of the 1-1000 Hg CI, 



