Besearches into the Nature of the Potato-Fungus. 
261 
others, equally large, rise from their pedicels, and are free in the 
surrounding space ; and two lie beside them quite free. These 
phenomena entirely disagree with all that is yet known of Pe- 
ronosj)orcce and Saprolegniecc. 
It is equally opposed to known phenomena that the " anthe- 
ridia " in question originate from a mycelium which is luxu- 
riantly ramified, and is throughout different and indeed anatomi- 
cally separate from that which supports the " oogonia." It is true 
that the branches of Peronosporece and Saprolegniece are often of 
very unequal thickness, and those which support antheridia often 
thinner than others. But when the relation between the two 
kinds of branches is traced, it is found that those which 
support antheridia almost always develop in proximity to the 
insertion of the oogonia belonging to them, and consequently a 
special antheridian mycelium by the side of one supporting 
ooffonia would be an unheard of coincidence in the families in 
question. 
One cannot, it is true, say that such phenomena are impossible 
in these families. They would however require to be regarded 
as peculiarities in the highest degree remarkable in the potato- 
fungus if the explanation of the doubtful organs were otherwise 
beyond question ; taken by themselves, they not only do not con- 
firm this explanation, but go decidedly against it. 
I look in vain for other reasons in support of this explana- 
tion, or to establish even its probability. Grant that those 
warty bodies which resemble the oospore of P. Arenarice are 
really oospores, it was surely necessary, at the least, to give a 
detailed account of their development from the supposed oogonia 
and antheridia of the macerated preparation, in order to establish 
the correctness of the explanation given of these doubtful bodies ; 
but that has not been done. I have myself endeavoured to fill 
up this lacuna by examining preparations of Mr. Smith's, which, 
he has been so good as to communicate to me through Mr. Car- 
ruthers, but I have come to an opposite result. 
The two preparations which I examined were mounted on glass, 
and bore the inscription " Peronospora infestans, Mont. Rest- 
ing-spores and oogonia." Both contain, in the liquid in which 
they are preserved, much granular detritus, obviously the product 
of the maceration of the potato ; then there are distinctly septate 
threads of mycelium, which, from their form, I should class with 
Oidium lactis, the more so because there likewise exist in the pre- 
parations conidia of this common mould, which also grows under 
\vater ; and lastly, numerous isolated globular bladders, some- 
what larger than the oogonia of Pijthium vexans. These last 
organisms have a moderately thick membrane, which in many 
cases is quite smooth, while in others the outer surface is irre- 
