32 
Journal of Agricultural Research 
Vol. XI, No. i 
SPECIFIC CHARACTERS OF THE PARASITE 
2 8 12 18 sp iypB 95 
Tylenchus penetrans, n. sp.—* *'" ' ' viV *"u •’ “ The thin, color¬ 
less, transparent, naked cuticle is traversed by about 400 plain transverse striae, 
resolvable with moderate powers. There are six amalgamated lips 
on which the cuticle is thickened in such a way as to have the 
appearance of a frontal cap. This cap is apparently built from about 
three ordinary striations. There are no labial papillae. The spear 
is about twice as long as the lip region is wide, and is composed 
of two distinct regions. The posterior half is a cylindrical shaft 
about pin diameter. At the very base this portion expands 
into a 3-lobed bulb having a diameter twice as great as that of 
the shaft itself. The anterior half of the spear tapers. Nothing 
is known concerning the lateral organs. There are no eye spots. 
The esophagus may be traced backward from the median bulb a 
distance approximately equal to the corresponding body diame¬ 
ter, and ends more or less indefinitely. The anterior ovary is 
elongated and outstretched and ends at a point as far behind 
the median bulb as the latter is behind the anterior extremity. 
The eggs occur one at a time in the uterus, and segmentation begins 
before they are deposited. The eggs are thin shelled, elongated, 
fully twice as long as the body is wide, and about one-third as 
wide as long. Eggs found deposited by the nemas in the tissues 
of the host-plant measured 78 by 25 ju, and contained fully formed 
embryos with well-developed spears three-fourths as long as those 
of the adults (fig. 1). 
*750 
Fig. 3. —Tylenchus 
penetrans: Profile 
of the tail end and 
bursa of the male. 
The two posterior 
pairs of bursal ribs 
are very faint and 
easily escape ob¬ 
servation. Com¬ 
pare with figure 4. 
.T*.. 
4. 4.9 ,4.6 
The bursa surrounds the tail completely, 
springing from near the lateral lines at a point opposite the proximal ends of the two 
equal arcuate spicula. The general contour of the tail end of the male when viewed 
dorsoventrally shows no enlargement, the distance across the 
bursa being nowhere greater than the diameter of the body 
immediately in front of the anus (fig. 3 and 4). 
Habitat.—Parasitic in the roots of violets, Rhinebeck, New 
York; roots of camphor trees, Orlando, Florida; roots of Upland 
cotton, Millington, North Carolina, and Statesboro, Georgia; 
in potatoes, vicinity of Kalamazoo, Michigan. 
SUMMARY 
xm 
CSCM 
(1) A parasitic nema, Tylenchus penetrans , n. sp., 
has been discovered infesting the tubers of the potato, 
the feeding roots of camphor, the rootstocks of violets, 
and the roots of Upland cotton. 
(2) External indications of the presence of the 
nema are the existence on the roots or tubers of 
small, abnormal-looking areas, a few millimeters 
across, sometimes in the form of pimples, but more 
often in the form of slightly sunken, discolored areas. 
Each of these diseased areas when fully developed contains up to about 
50 specimens of T. penetrans in various stages of growth. 
tm 
Fig. 4. —Tylenchus pene¬ 
trans: Ventral view of 
the tail end of the male. 
Compare with figure 3. 
The two pairs of ribs 
near the terminus were 
nearly invisible in this 
specimen. 
* For explanation of formula, see appendix, p. 33. 
