Wilson : North American Peronosporales (55 
cessively gelatinized walls. The solid walls of these bodies are 
smooth, thick, and brown. Only in a single instance was anything 
observed which was analogous to the formation of an oosphere. 
One figure (no. 15) is especially interesting as it is very sug- 
gestive of the type of antheridia which have recently been de- 
scribed for several species of Phytophthora. It may be that the 
majority of these bodies are chlamydospores, a structure which is 
known for several species of the genus. 
In the later cultures a very different type of resting spores were 
found. These are produced, as were the others, either terminally 
or intercalary, have a single cell-membrane which is thickly 
covered with spiny tubercles. These resting spores measured 
20-33 n in diameter. The wall has two or three spots which 
rupture easily and suggest germ pores. The younger stages of 
these bodies showed 30-50 nuclei. As no bodies corresponding to 
antheridia were found there is no proof that these bodies are 
sexual spores, nor is any such claim advanced for them. The 
exact status of these bodies appears not to have been exactly 
clear to the authors as the following quotation shows. “ These 
spores have been found in nine different strains of Phytophthora . 
These nine strains were carried continuously in culture for over 
three years without anything occurring to throw suspicion on their 
purity. . . . This fact seems to rule out the occurrence of any 
ordinary type of saprophyte. ... It is not believed possible that 
any admixture of saprophytic growth could have entered all cul- 
tures alike, much less persist without detection. The only sug- 
gestion that seems worthy of further consideration is that these 
resting spores might belong to a species parasitic upon Phytoph- 
thora as Piptocephalis is upon certain moulds. De Bary, indeed, 
suggests such a relation as possible between Artotrogus hxdno - 
sporus and Pythium debaryanum. It would seem to us almost 
impossible, however, that such a condition should occur in all 
nine cultures alike and persist without detection during so long a 
period and under such varied cultural conditions” (pp. 68, 69). 
These conflicting observations left the question of oospores of 
P. infestans in a most unsatisfactory condition until the appear- 
i ance of a paper by Pethybridge and Murphy (1913) which pre- 
sents evidence of a nature well calculated to set the matter at rest 
II . i 
