134: The Potato Fungus. By Worthington G. Smith. 
every possible way. I have frequently seen similar secondary 
threads branched. 
During the last hours of completing the last two Plates illus- 
trative of the Potato fungus, a new and curious fact came to light. 
On examining the oospores in saccharine fluid, I observed some of 
the discharged bladders to be carrying from two to four secondary 
bladders inside (X) ; these secondary bodies were in their turn 
expelled, and grew and produced mycelium as at Y, Y, Y, whilst 
a few of the same secondary bladders burst and produced from 
three to six very small zoospores, generally only three. It is a 
most singular fact that these secondary bladders and zoospores are 
exactly the same in size with De Bary's Pythium vexans, and 
about one-sixth or eighth of the bulk of the resting spores from 
which they were discharged. With this exception there has not 
been the slightest approach in any of my material to organisms 
which might be referred to Pythium. Mr. Plowright writes : 
" None of my oospores ever burst and produced Pythium or 
Pythium-like spores." 
My material has contained a large number of dead mites and 
aphides and a few nematoid worms ; the oogonia and threads were 
to be seen in all parts of the dead insects, but not in the worms. 
De Bary, in reviewing my observations, says ; Even if the 
often-mentioned warty bodies were hibernating oospores of Phy- 
tophthora (Peronospora), like the similar oospores of P. Arenarise 
which resemble them, we should not gain much information bear- 
ing upon these questions, since their occurrence is, at the best, 
extraordinarily rare." This sentence is very erroneous, for although 
the bodies were apparently rare when I first recorded their dis- 
covery, they were not necessarily so in a state of nature, for on 
continuing the experiments after my first essay was written, the 
resting spores were produced in myriads, and that too within 
the tissues of a comparatively few leaves. During the present 
spring I have sent mounted preparations of the mature (or almost 
mature) resting spores to many of the foremost cryptogamic 
botanists of Europe, but not one has denied their possible identity 
with Peronospora infestans. 
For more than thirty years our Potato crops have been 
systematically destroyed by two virulent fungi, viz. Peronospora 
infestans and Fusisporium Solani ; these two parasites almost 
invariably work in company with each other ; they suddenly 
appear for a few weeks, destroy our crops, and vanish for ten 
or twelve months, then reappear and repeat the work of destruc- 
tion. I claim for my work that it is new, and that it has proved 
how both these fungi hide and sleep through eleven months of the 
year. As I have kept the resting spores of both parasites alive 
artificially in decayed Potato leaves in water, in moist air, and in 
