26 
BULLETIN S42. U. S. DEPARTMENT OF AGEICULTURE. 
In Table IV also are given the data secured by treating soaked 
galls with mercuric ehlorid. copper sulphate, and sulphuric acid. 
As can be seen, these results are comparable to those obtained with 
formaldehyde, namely, that the nematode is strikingly resistant to 
the chemicals and that treatments with these chemicals which are 
not injurious to the wheat fail to kill the larva?. 
LARVJE OUTSIDE OF THE GALLS. 
The method of treating unprotected larva? outside of the galls 
consisted in placing the actively moving nematodes, usually those 
removed from a single water-soaked gall, in the solution in a Syra- 
cuse watch glass. From the time the larva? were put into the dish 
they were kept under continual microscopical observation for sev- 
eral hours, or a day. until after all signs of life had disappeared or 
until the treatment was discontinued. At the end of the experiment 
the percentage of larva? living was noted, and this, with other data. 
is given in Table V. 
Table V. — Effect of various rhrmicahs on unprotected larva* of the wheat 
nematode outside of galls. 
Treatment. 
Chemical. 
>treneth. 
Exposure. 
Date. 
Number 
of lots of 
larvae. 
Larva? 
living 
(per 
cent). 
Formaldehyde . 
Mercuric ehlorid . 
Copper sulphate. 
I§ per cent . . 
1 per cent . . 
Li per cent . 
Check. 
Tap water . 
Hours. 
fc 
1: 120.. 
1: 100.. 
1: 50 
1: 25 
1: 1,000... 
2: 1..000... 
4: 1,000... 
10:1,000.. 
5 per cent 
10 per cent 
15 per cent . 
Days. 
Minutes. 
SO 
May 31 
June 1 
May 31 
June 1 
May 14 
Mav 17 
May 31 
June 1 
May 14 
May 17 
Mav 14 
Mav 17 
May 31 
June 1 
May 31 
June 1 
May 31 
June 1 
...do 
May 16 
June 1 
Mav 17 
May 1-3 
June 1 
Mav 17 
May 16 
June 1 
Mav 17 
..do... 
June 1 
May 17 
June 1 
May 17 
June 1 
/Mav 14 
\May 31 
001 
A study of Table V shows that the larva? are extremely resistant 
to the toxic action of the chemicals, living -i hours and 55 minutes 
