14 DEPARTMENT OF AGRICULTURE
 Furthermore, for a proper assay of the status of a given plant asd
host, it should be ascertained whether the nematode is actually p
during progeny on it. For a demonstration of this point root-knot nejA
todes may serve again. Our observations appear to show that these p
parasitic larvae enter the roots or subterraneous stem and leaf form.


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 Figure 8.-A. Root-knot infected bean seedling with galls also on the .leaves (I
arrow). B. Root-knot infected bean seedling with galls also on the stem (at arrows
C & D. Malformed and dying bean seedlings with heavy infection of root-knol
nematodes; 1/2 normal size. Attention may be called to the fact that such hea4
invasions of seedlings, leading to the ultimate death of the plants before the invading
nematodes have time to produce progeny, may lead to such a reduction in thl
number of nematodes that a replanting with beans may be fully successful.
tions of almost any type of plant in spite of the fact that, in most case
they are unable to develop in them and to produce progeny. In 1931
it was found that the root tips of French marigolds (Tagetes hybrids
were heavily invaded by larval root-knot nematodes, while galls witE
full grown females producing egg masses were observed in only smaj
numbers. Upon closer study it was shown that most of the larval nema-
todes that invaded these roots were unable to develop to the adus
stage and died before reaching it. Obviously these resistant marigold,
did not furnish the invading root-knot larvae with the proper food, oI

 I