127 
Possibly the lines seen on the surface are due to this lighter colored 
substance between the prisms. The endospore is 2 to 3 p thick and 
homogeneous. Undoubtedly its composition is quite different from that 
of the epispore. The sphere bounded by the endospore is very constant 
in size, being 28 to 38 /q mostly 29 to 34 p. 
The mycelium is very variable in diameter, and is furnished with 
abundant haustoria. The haustoria are filiform and almost always un¬ 
branched. Near the base they are gradually narrowed till, at the point 
of union with the mycelium, they are only about half as thick as at the 
distal end. They are usually very much bent and contorted, often ap¬ 
pearing like a tangled mass of filaments. They often attain considera¬ 
ble length, sometimes as much as 40 p. 
As I have already described* the conidiophores and conidia I 
need not speak of them here, except to mention that in examining co¬ 
nidia that had been treated with warm KHO solution, and thus ren¬ 
dered lifelike in shape, I saw a number that had still attached lateral 
germ tubes. I have, finally, to report a most remarkable form of the 
conidial fructification in the Montana specimens collected by F. W. 
Anderson. The conidiophores are less branched than in the Kansas 
specimens, and the antepenultimate and penultimate branches are 
shorter and the ultimate are shorter still. All branches are strongly 
tinged with fuliginous, while the Kansas specimens show only faint 
traces of coloration in the conidiophores. The most remarkable char¬ 
acter of these specimens is the fact that the conidiophores issue from 
the stomata in dense groups often comprising 10-15 or even more mem¬ 
bers. In the Kansas specimen of P. echinospermi the conidiophores arise 
singly or more often in groups of 2-5 through the stomata. For the pres¬ 
ent, till more specimens can be obtained and, if possible, oospores be 
found, I think this form had best be referred doubtfully to P. echinos¬ 
permi. 
I have compared P. echinospermi very carefully with P. cynoglossi 
Burrill and find besides the differences in the conidiophores and 
conidia which I pointed out in 1889, considerable differences in the 
oospores. The oospores of P. cynoglossi differ from those of P. echinos¬ 
permi in being considerably smaller (25-30 p diameter sec. Burrill, but 
in what I have measured 27-40 p mostly 27-34 p diameter), in having 
usually a thinner epispore which does not show the peculiar surface 
markings, and is indistinctly if at all radiate in structure. 
Peronospora myosotidis De Bary, and P. asperuginis Schroeter, differ 
from P. • echinospermi in the conidial fructification in which they ap¬ 
proach more nearly P. cynoglossi. If the published descriptions are at 
all to be relied upon the oospores of these two species are very different 
from those of P. echinospermi. Unfortunately I have not been able to 
find any oospores of either of these species in the specimens at my dis¬ 
posal. I append measurements (all given in p's) of oospores of P. 
*A list of Kansas species of Peronosporaceae, loc. cit., pp. 77-78. 
