256 
Journal of Agricultural Research 
Vol. VIII, No. 7 
(9), and Rorer (27) observed bodies which they took to be oospores. 
Von Faber states that he found oospores, but failed to find antheridia 
and oogonia; Coleman that the oospores “almost always fill the oogonial 
cavity so completely that the oogonial wall can be made out only with 
difficulty”; and Rorer refers to them as “ parthenogenetic oospores.” 
In a pure culture of P. faberi originally obtained from Dr. Coleman 
an abundance of these bodies were produced. A great deal of time was 
devoted to their study in fresh as well as in sectioned and stained mate¬ 
rial. As a result of these studies the writer is convinced that they are 
not parthenogenetic oospores but are multinucleate vegetative bodies, 
serving the same function that chlamydospores serve in other groups of 
fungi. Dastur (10) observed similar bodies, which he termed “resting 
conidia,” in P. parasitica , and pointed out that there is little probability 
of their being parthogenetic oospores. He says: 
They are over twice the size of normal oospores and that from the very beginning 
of their development they are thick-walled and slightly yellow tinted, while par¬ 
thenogenetic oospores have their origin in thin-walled and hyaline oogonia, which 
on failing to come in contact with the antheridia after reaching maturity undergo 
the same change, at least outwardly, as they would have if they had been fertilized. 
The chlamydospores were produced in culture in P. faberi , P. para¬ 
sitica , P. jatrophae t and P. nicotianae . In all of these their general appear¬ 
ance is the same. Their contents are similar to that of the conidia, being 
granular, with one or more vacuoles, and are illustrated in Plates 76 and 
77. It is significant that in all forms which produced an abundance of 
chlamydospores no oospores were produced in the cultures. 
Measurements of chlamydospores. —Although similar in general 
appearance, the chlamydospores differ in size in the different species, 
and this difference is constant no matter on what media the culture is 
grown. As in the case of the conidia, great variation in size occurs 
within the species; hence, in order to determine the predominating size, 
as well as distribution in the various classes, 400 measurements of their 
diameters were made. The results are given in Table III. As will be 
seen from this table, the chlamydospores may vary in size from 17.5 to 
59.5 /z, and P. faberi is the only one which has a predominating class of 
more than 32.5 /z. The difference in size of the predominating class of 
the chlamydospores of P. faberi and of the remaining three is sufficient 
to be employed in their separation. 
