PLANT DISEASES 409 
three feet high, we noticed many diseased ones with brown or wilted leaves and 
stalks, and through the kindness of the director, Dr. Corbisier, were able to secure 
a large number of the diseased and healthy plants for examination. From a 
comparative study of these it was possible to show that in the diseased plants 
the terminal roots were not of the normal gray color observed in the healthy ones, 
but were more or less of a dark brown color and showed in places numerous small 
areas where decortication of the bark had taken place (Number 346). Scrapings 
from the roots of the diseased plants revealed large numbers of larval forms and 
adults of the genus Tylenchus which are characterized by the buccal armature 
and the character of the oesophagus. Since our return to the United States these 
parasites have been kindly studied by Dr. Cobb who concluded that the parasite 
iS a Species new to science which he has described and named, as T'ylenchus 
alatus (Number 347), this name being particularly applied on account of the 
broad, wing-like expansion of the caudal extremity. Dr. Cobb has kindly con- 
sented to the publication of his description of this species which is given on 
page 487. The parasites were found in the Cinchona plants almost anywhere in 
the roots as far as the crown. The adults, male and female, were also found in 
smaller numbers upon and beneath the bark of the roots. In places where the 
decortication of the bark had taken place there was sometimes a secondary in- 
fection with a fungus growth, a few mycelial threads of which were visible on the 
surface but did not penetrate into the interior of the root. This parasite, as Cobb 
has pointed out, has a very well developed, long, typical tylenchoid spear. It 
is apparently by this structure that it is enabled to pierce the bark of the roots 
and, being very active and muscular the worm is able to work its way between 
the covering of the root and the central core. This disease apparently has not 
previously been described in Cinchona plants. Quinine production in the Congo 
is clearly a matter of considerable importance as the Belgian Government here 
alone uses some thousand kilos annually. In Liberia Cinchona has not as yet 
been cultivated. 
Infection of rubber trees. Rubber cultivation is evidently of very great im- 
portance in Liberia, particularly in connection with the extensive activities of 
the Firestone Plantations Company. However, we did not find any serious 
disease of the rubber trees there. In fact, the only infection noted was the 
growth of a fungus which occurs in black lines along the trunk of the trees 
(Hevea brasiliensis) where they have been denuded of bark in collecting latex. 
This fungus was identified by our botanist, Dr. Linder, as Phytophthora meadii 
(Petch). Linder, in describing this disease, points out that the first symptom of 
the condition is the cracking in vertical lines of the cortex that remains after the 
outer layer is removed in tapping. Around the cracked lines there is a depressed 
area underneath which the tissue is blackened. At the same time the cambium 
layer is killed to a depth of a quarter of an inch. With age, the blackening be- 
comes evident externally, the lines elongating and tending to fuse, thus forming 
a darkened area with a ragged diffuse outline. In wet weather this blackened 
surface is covered with a white, cottony layer in which the zoosporangia of 
Phytophthora are produced. Linder has illustrated this condition and made 
