48 Massee. — On the presence 
whether the mycelium originated in the leaf from germinating 
spores of Uromyces and passed down the petiole into the 
tubers, or spread from the latter into the leaf, but it will be 
shown later on that, when the spores germinated, they sent 
germ-tubes into the tubers of the Ranunculus. 
Being desirous of ascertaining whether the clavate body 
mentioned above was in any way connected with the Aeci- 
dium , numerous young unopened peridia were cut, but with- 
out result, as when the presence of the parasite is manifested 
by elevation of the leaf-epidermis, even before the latter is 
ruptured by the peridia, the weft of mycelium has undergone 
important changes ; and it was not until I had made sections 
through those portions of the leaf first showing traces of the 
fungus in the form of a slight discoloration or the appearance 
of spermogonia, that I discovered the clavate body in a ball 
of mycelium which represented the initial stage of an 
Aecidium. In this instance the object of search was in a 
more advanced stage (Fig. 2), clearly showing it to be an 
oogonium, accompanied by an antheridium. The oogonium 
was much larger than the one first seen, in form irregularly 
oblong, measuring about 50 x 25 j u, terminal on a thread from 
which it was cut off by a transverse septum, and containing 
finely granular protoplasm with numerous refractive globules. 
1 could see no trace of a nucleus without reagents, which I did 
not apply, being desirous of observing the development as 
long as possible. The antheridium is cylindrical, about 40 x 
12 fx, and like the oogonium filled with protoplasm and oil 
globules and termianted by a short lateral branch, springing 
from a thread distinct from the one supporting the oogonium, 
so far as I could trace the two in the mass of mycelium. The 
antheridium is cut off from its supporting hypha by a trans- 
verse septum. The point of contact between the antheridium 
and oogonium was on the side turned away from the eye, so 
that I am unable to state the exact manner in which fertilisa- 
tion is effected. After remaining for two days in water with 
2 per cent, of glycerine, the antheridium became empty and 
shrivelled ; the oogonium during the same period having in- 
