116 
minutes to over 2 hours. The sucking process 
also is of long duration, continuing without 
interruption in some individuals for well over 
an hour, but it may be interrupted and resumed 
many times without the nematode’s moving to 
another feeding site. Pulsation of the bulb is 
vigorous and readily observable even in young 
larvae, but beyond seeing that the valve plates 
are pulled well apart and then come back to- 
gether at each beat it has not been possible to 
analyze the motion. The rate is variable between 
individuals, commonly ranging between 80 and 
200 beats per minute. Minor irregularities and 
an occasional beat that may represent a different 
action of the valve are sometimes seen. 
Many observations of host cell protoplasts 
indicate that no great disturbance results dur- 
ing or soon after feeding. Root hairs are es- 
pecially favorable for such studies but the active 
protoplasts of epidermal cells may often be seen 
when the object is appropriately oriented to the 
source of light and when the root surface is 
clean. When the stylet is first inserted, its tip 
probably extends through the cytoplasmic en- 
velope into the central vacuole. It soon becomes 
surrounded by a dome of granular material 
delimited by what appears to be a very thin 
membrane. During pulsation of the median 
bulb, this dome enclosing the stylet tip shows 
synchronous pulsation. Otherwise it is motion- 
less, and no flow from or into the stylet has 
been detected. 
Whether the nematode is sucking or lying 
at rest, and whether one, two, or even three are 
feeding simultaneously from a single cell, pro- 
toplasmic streaming of apparently normal nature 
and rate continues without interruption. Some- 
times the nucleus moves to a position near a 
stylet tip; occasionally the dome of cytoplasm 
over the tip appears to be a focus of streaming 
strands of cytoplasm; but more commonly the 
stylet tip and its surrounding mass appear to 
be only a minor obstruction past which the 
cytoplasm flows. This has been true of the sev- 
eral host species studied in detail. Streaming 
continues also after the stylet is retracted and 
PACIFIC SCIENCE, Vol. Ill, April, 1949 
the nematode moves away. Even after a female 
had fed from one cell or a small group of cells 
of a pineapple root long enough to lay 13 eggs, 
no definite pathology could be distinguished. 
Very heavily parasitized roots of cabbage seed- 
lings grown in fine sand, fixed, cleared, and 
stained have shown as many as six larvae and 
females all with their stylets in a single epi- 
dermal cell, without any conspicuous alteration 
of its protoplast. 
This paratylench appears to be relatively 
sedentary once it has begun to feed in a suit- 
able cell, for certain nematodes in marked loca- 
tions have been observed during several days 
to be feeding either in the same cell or in cells 
lying close together and with the body position 
changed only moderately. One well-isolated 
female feeding on pineapple roots was found 
with a loose cluster of four eggs. Four days later 
there were 12 eggs. The following day there 
were 13, and the nematode lay free in the soil 
with its stylet retracted. Another female appar- 
ently laid 11 eggs in two loose clusters very 
close together, and was still feeding after these 
had begun to hatch. Between the sixth and sev- 
enth days of observation, two larvae began to 
feed very close to empty egg membranes of one 
of these clusters. 
Observation of the living material gives the 
impression that this paratylench is strictly ecto- 
parasitic, for the feeding of many individuals 
during prolonged periods may be observed 
without detecting any attempt to use the stylet 
to break down a cell wall or otherwise to force 
an entry. When roots that have been stained 
and cleared are examined, however, females, 
young, eggs, and even a few males may be 
found within epidermal cells or located either 
within or between cells of the cortex. These 
always are few in proportion to the numbers 
that were present on the root surface, and many 
if not all of them entered through wounds made 
by other agencies. Wounds made by emergence 
of lateral roots allow entry into intercellular 
spaces deep within the cortex. Sharp sand par- 
ticles between root and glass in observation 
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