The Besting S;pores of the Potato Fungus, By W, G. Smith. 113 
Peronospora when sucli an authority as Mr. Berkeley * considers 
one of the Saprolegnieae (Achlya) " may be an aquatic form of 
Botrytis Bassiana " — the silkworm disease. 
The common fungus which attacks flies (so frequently seen on 
our window-panes in autumn), Sporendonema muscse, Fr., is said 
to be a terrestrial condition of Saprolegnia ferax, Kutz., which 
latter only grows in water ; and if a fly infected with the fungus 
be submerged the growth of the Saprolegnia is the result. It 
would now seem to be somewhat the same with the Potato when 
diseased, in the fact that when submerged a second form of fruit is 
produced. 
Between the two moulds, Botrytis and Peronospora, there is 
little or no difierence ; the characters of Corda, founded upon the 
continuous or septate filaments, cannot be relied upon, and even 
De Bary himself figures P. infestans with septate filaments, like 
a true Botrytis. The intimate connection, however, between the 
Saprolegnieae and some moulds cannot be denied, as the instances 
above cited clearly show ; and I am therefore disposed to think that 
the fungus which produces the Potato disease is aquatic in one 
stage of its existence, and in that stage the resting spores are 
formed. 
Keference may here be made to the bodies found germinating 
in the intercellular passages of spent Potatoes by Dr. Montague 
(Artotrogus), and referred by Mr. Berkeley to the Sepedoniei. 
Ever since Mr. Berkeley first saw these bodies he has had an 
unswerving faith in the probability of their being the secondary 
form of fruit of Peronospora infestans, but unfortunately, as far as 
I know, no one has ever found a specimen of Artotrogus since 
Montague. 
The question may therefore be naturally asked, — How does 
Artotrogus agree with the presumed resting spores here figured 
and described? And has Mr. Berkeley been right or wrong iii 
clinging so tenaciously to his first idea ? Fortunately for the 
investigation of the Potato disease (which can never be cured 
till it is understood), Mr. Berkeley has given in the 'Journal 
of the Eoyal Horticultural Society ' the number of diameters his 
figures are magnified to, and I have here engraved those figures 
so as to correspond in scale with my own drawings, which latter 
are sketched with a camera lucida. It will be seen that they 
are the same with each other both in size and habit, with the 
exception of the processes on the mature spore of Artotrogus — 
which processes may possibly be mere mycelial threads, or due to 
the collapsing of the inflated epispore. The reason these resting 
spores have evaded previous search is that no one has thought of 
* * Micrographic Dictionary/ p. 6. 
