112 The Resting Spores of the Potato Fungus. By W. G. Smith. 
septate, and sometimes more or less moniliform or necklace-like. 
Both oogonium and antheridium are very similar in nature and 
size to those described as belonging to Peronospora alsinearum 
and P. umbelliferarum, and this is another reason (beyond my 
seeing undoubted P. infestans on Potato leaves at the beginning 
of June) why I am disposed to look upon these bodies as the 
oogonium and antheridium of the Potato fungus. 
The larger bodies are at first transparent, thin, pale brown, 
furnished with a thick dark outer wall, and filled with granules ; at 
length a number (usually three) of vacuities or nuclei appear. 
The smaller bodies are darker in colour, and the external coat is 
apparently marked with a few reticulations, possibly owing to the 
collapse of the outer wall. I have observed the two bodies in 
contact in several instances. After fertilization has taken place, 
the outer coat of the oospore enlarges, and soon gets accidentally 
washed off in water. Both antheridium and oogonium are so 
slightly articulated to the threads on which they are borne that 
they are detached by the slightest touch, but with a little care it is 
not really difficult to see both bodies in situ ; and my observations 
lead me to think that conjugation frequently takes place after both 
organs are quite free. The antheridia and oogonia are best seen 
in the wettest and most thoroughly decomposed portions of the 
tissue of the decomposing tuber, but they occur also in both the 
stem and leaf. I consider Mr. Alexander Dean’s remark, as re- 
ported in the ‘Gardeners’ Chronicle’ for June 19 last, p. 795, to 
have a distinct bearing on this point, where he says, “ In all cases 
where the seed tubers were cut they were quite rotten.” 
Before I referred to De Bary’s measurements of similar organs 
in other species of Peronospora I was disappointed with the results 
of my observations, and felt disposed to refer the bodies and 
threads in the Potato leaves to Saprolegnia, but a glance at the 
figures now published and the similar figures copied from De Bary 
to the same scale, will show that if the bodies observed by me are 
Saprolegnia-like, the oogonia and antheridia figured by De Bary 
show an exactly similar alliance. Still, as the Saprolegnieae are at 
present defined, I am by no means inclined to describe the bodies 
observed by me as really belonging to that tribe of plants. 
The Saprolegnieae have the habit of moulds and the fructifica- 
tion of Algae, and they live on organic matter, animal and vege- 
table, in a state of putrefaction in water. One of the best known 
of these plants is Botrytis Bassiana, the parasite which causes the 
disease of silkworms. Now the genus Botrytis amongst fungi is 
almost or quite the same with Peronospora, to which the Potato 
disease belongs ; and I consider it a strong argument in favour of 
my Saprolegnia-like bodies being the oogonia and antheridia of the 
