NEMATODE DISEASE OF WHEAT. 19 
tive organs. The latter extends as a tube of about uniform cliam- 
eter nearty up to the esophagus, folds back for a short distance, and 
terminates in a closed end. This tube is usually well filled with 
developing or mature spermatozoa, which with the aid of a copulat- 
ing organ, the spieula,- located near the sexual opening, may be 
ejected during coition. Unlike the intestine of the female and 
similar to that of the larvae, the intestine of the male extends, largely 
undisturbed by the reproductive system, from the base of the eso- 
phagus nearly to the anus as a tube of uniform diameter. 
The male is capable of movement during practically its entire life, 
retains its larval shape, and probably copulates only once. Slug- 
gishly moving males are often found in galls which contain only 
the shapeless disorganized remains of females. As has been stated, 
males and females occur in about equal numbers. 
EFFECT OF HIGH TEMPERATURES ON THE LARViE. 
LARV^ INSIDE OF THE GALLS. 
In order to determine the maximum thermal death point of the 
larvae, the writer has treated a large number of galls with hot water 
at various temperatures. The results of these tests are presented 
in Tables I and II. Galls soaked several hours or days in unheated 
tap water were used in obtaining the data given in Table I, while 
in Table II the data were obtained from treating the dry mate- 
rial. In all cases the same method was used in applying the hot- 
water tests. It consisted in submerging lots of two to six galls for 
the desired length of time in a large volume of water, the tem- 
perature of which did not vary during the course of the experiment 
more than 1 degree above or below that required, and usually varied 
less than half a degree in either direction. Following the treat- 
ment, each gall was' placed in distilled water in a Syracuse watch 
glass, then carefully opened with sterilized instruments, and the 
larval contents microscopically examined repeatedly for several days 
afterward. In the first few experiments larvae were discarded after 
having been under observation for one day subsequent to treatment, 
but it was soon discovered that some of the organisms showed signs 
of life at a later date, so in all succeeding experiments the larvae 
were observed 'over a period of two to nine days. A total lack of 
movement of the larvae in combination with the coagulation of their 
internal granular contents was taken as the criterion of death. The 
largest number of larvae found to be living while they were under 
observation was roughly estimated in the percentage of the average 
number of individuals (about 1,500) contained in each gall. All the 
nematode galls used in these tests were from the same source, namely, 
a collection made on a farm near Union Mills, Va. 
