224 
Journal of Agricultural Research 
Vol. II, No. 3 
duced during these operations. Therefore, before the capsule was buried 
in the soil, it was placed on blotting paper, so that as much water as 
possible might drain away. This left 
the capsule in a condition to reabsorb 
moisture. The soil about the potted 
Citrus seedling to be used in the ex¬ 
periment was previously allowed to 
become somewhat dry; in fact, was 
allowed to go without water until the 
seedling showed the first signs of dis¬ 
tress. The prepared capsule was then 
placed in the pot adjacent to sound 
young Citrus feeding roots and the soil 
x 3o .. , replaced in the pot (see fig. io). The 
Fig. 8.—Two half-sections of citrus root magni- Citrus seedling was then at once 
fied 30 diameters: a. Healthy root; 6 diseased water ed, SO that the capsule was given 
root. A female specimen of Tylenchulus ’ 1 & 
semipentrans is shown at c with her head end an immediate opportunity tO absorb 
embedded in the root. Note that the outside 
portion of the diseased root, shown light, is 
nearly detached from the central axial portion, 
shown black. Compare with figure 3. 
soil moisture that might be described 
as “of a citrous character.” 
In the spring of 1913a number of ex¬ 
periments were started with a view to 
ascertaining the length of time required 
for the larvae of Tylenchulus semipene- 
trans to become adult. Tor this pur¬ 
pose potted grape-fruit seedlings of a 
size and character illustrated in figure 
10 were used. Material derived from 
Tylenchulus-infested Citrus roots was 
added to the water supplied to the seed¬ 
lings. In most cases some of the surface 
soil was removed, and the infested 
water applied several days in succes¬ 
sion in such a way that there could be 
no doubt that an abundance of the Fig. 9 .—Tylenchulus semipenetrans : Posterior 
living larvae had come m contact with islocatedoutsideo , the citrus root, compare 
the roots. Previous examinations in¬ 
dicated that few, if any, of the female 
larvae added to the water were advanced 
beyond the earliest stages shown in the 
illustrations. Check plants were sub¬ 
jected to the same treatment as the 
infested plants, with the exception that no material containing T. semi¬ 
penetrans was added to the water. There was no difficulty in rearing 
figures 1,3,8, and 13. a, Blind end of the coiled 
single ovary; 6, anterior portion of ovary; c, 
posterior portion of ovary; d , renette cell; 
e, duct of the renette cell; /, excretory pore; 
g, vulva; h t terminus; i, uterus; j, cuticle; k t 
somatic granule; /, function of ovary with 
uterus; m, posterior end of ovary with ovum 
ready to enter uterus. 
