22 



BULLETIN" 842, U. S. DEPARTMENT OF AGRICULTURE. 



to 12 minutes in water at a temperature of 54° to 56° C. If the 

 statements of these investigators, however, were supported by ex- 

 perimental data these were not presented, and furthermore, they 

 failed to mention the important point as to whether the} 7 were treat- 

 ing dry galls or those that previously had been soaked in water. 



Table II. — Effect of hot-water treatment on larvce of tlie wheat nematode in- 

 closed in' dry galls. 



Lot. 





Hot- water treatment. 



Number 















of galls, 









each con- 









taining an 

 average 

 of more 



than 1,500 

 larvee. 



Date, 

 1918. 



Temper- 

 ature 

 CO.). 



Duration. 









Minutes. 



6 



Mar. 13 



50 



10 







June 5 



50 



15 



6 



Mar. 13 



50 



20 



5 



June 5 



50 



20 



5 



June 17 



50 



30 



5 



...do 



50 



35 



5 



...do 



50 



40 



5 



...do 



50 



45 



5 



June 5 



52 



10 



5 



...do 



52 



15 



5 



...do 



52 



20 







June 17 



52 



25 







June 5 



54 



10 



6 



Mar. 13 



54 



lij 



5 



June 5 



54 



15 



5 



...do 



54 



20 



o 



...do 



56 







5 



...do 



50 



10 



5 



...do 



56 



15 







June 17 



56 



15 



6 



Mar. 13 



58 







5 



June 5 



58 







6 



Mar. 13 



58 



10 



o 



June 5 



58 



10 



6 



Mar. 13 



60 











June 5 



60 











...do 



60 



10 



6 



Mar. 13 



0) 



Days. 

 3 



5 



June 5 



0) 



4 



Extent of 

 observa- 

 tion after 

 treatment 

 (days). 



LarvEe active (per cent). 



In each gall at last 

 examination. 



2 



3 



4 



5 











15 



5 



35 



90 



30 



90 



75 







2 







40 



90 



75 



80 



.5 



50 



25 



10 



20 







40 







15 



8 







5 



.06 



15 



20 







SO 



75 



45 



90 



65 







10 







20 







70 







20 



15 



55 



40 







60 







60 























35 



10 



20 



















90 



45 



60 



80 



75 



40 



































.2 















75 











65 



90 







80 



.06 















65 



90 







75 



2 



3 



80 







SO 























• I 



95 



95 



95 



95 



95 



95 



95 



95 



Average- 



In 

 each 

 lot. 



In 

 each 

 treat- 

 ment. 



No. 1. 

 No. 8. 

 No. 2. 

 No. 9. 

 No. 2 ! 

 No. 23 

 No. 20 

 No. 27 

 No. 10 

 No. 11 

 No. 12 

 No. 2? 

 No. 13 

 No. 5. 

 No. 14 

 No. 15 

 No. 16 

 No. 17 

 No. 1? 

 No. 23 

 No. 3. 

 No. 10 

 No. 4. 

 No. 2 •■ 

 No. 6. 

 No. 2 1 

 No. 22 



Check 

 Do. 



3 95 



4 ; 95 



3.3 

 56 



8.5 

 65 

 29 

 14 



5.0 



7.1 

 65 

 17 

 36 



26.2 

 24 





 13 



6 

 55 

 21 







.2 

 18.6 

 41 

 16 

 41 



47.5 

 30 

 x 



95 

 95 



3.3 



56 



•36.7 



20 



14 

 5.6 

 7.1 



65 



17 



36 



26.2 



24 



6 

 55 

 21 



^95 



1 Room temperature. 



LARVAE OUTSIDE OF THE GALLS. 



Active larvae liberated from galls were exposed to hot water in 

 the following manner in order to ascertain their response to high 

 temperatures. By means of a glass dropper about 300 nematode 

 larvae were transferred to diminutive bags of silk and then placed 

 in a large receptacle of water of the desired temperature. After a 

 specified time the bags were removed, the contents of each immedi- 

 ately emptied into distilled water in a Syracuse watch glass, and 

 the larvae examined microscopically on each of several days follow- 

 ing the treatment. The highest percentage of nematodes found living 

 at any one observation was recorded and is presented in Table III. 



•uxi 



