98 MR. C. B. PLOWRIGHT ON CERTAIN 
spores upon Hawthorn, which result was obtained 26 times out 
of 30. The question presents itself, Are there two species of 
Gymnosporangium upon Juniperus Sabine, as there are upon 
J. communis? Simple as this question appears to be, it is by no 
means so easy to answer it. Had this been the case, I should 
not have needed to perform 53 cultures. 
In the first place, Does the Restelia on Crategus produced from 
G. fuscum differ from the Restelia from G. clavarieforme? Itis 
important to settle this point, because it might be alleged that 
these two Gymnosporangia were the same plant, differing only 
from each other in such particulars as may be due to the differ- 
ences of their respective host-plants. The Restelia on Crategus 
from G. fuscum differs from that of G. clavarieforme in the ` 
following points :—(1) the spermogonia are produced on more 
brightly coloured spots; (2) the spores are rather smaller; (3) 
the cells of the pseudoperidia are marked with delicate reticula- 
tions or longitudinal wrinkles, whereas those of G. clavariaforme 
are dotted with minute elevated points. 
With regard to G. fuscum, Kornicke *, several years ago, pointed 
out that the fungus as he found it near Kénigsberg differed very 
materially from the description given by De Candollet. In 
Körnicke’s plant the masses were thin and gelatinous, and dried 
upon the branches in thin lamin® ; whereas De Candolle speaks 
of his plant as being but little gelatinous, having a velvety 
exterior, and when broken in the dry state, the interior is white 
and cottony. But even this does not help us, for the plant, as I 
find it here, answers while young to De Candolle's description, 
and when old, especially in rainy weather, it agrees with Kor- 
nicke's. Still I am of opinion that there are two species of 
Gymnosporangia in G. fuscum, although, up to the present, I have 
been quite unable to separate them. 
Witb regard to the cultures of G. fuscum on Pyrus communis, 
19 experiments have been made, of which 18 were successful, 
while 6 failed. This large proportion of failures looks very much 
as if there was a second species which does not have its æcidio- 
spores on Pyrus. Furthermore, in my earlier cultures made in 
1882-83, I had a larger proportion of successes than I have had 
since that date. My earlier cultures were principally made with 
material from a Sabine bush which died in 1884. It must be 
* Körnieke, ' Hedwigia, 1877, p. 25. 
t De Candolle, Flor. Frang. vol. ii. p. 217. 
