THE POTATO FUNGUS. 
23 
of branching, nodose conidiophores. especially amongst the drier 
portions of the substance sent. I also see liniig conidia. I have 
seen many conidiophores with convoluted bases, but in the vast 
majority of cases long ere the conidia come the oospore is gone ; 
I see the granular protoplasm distinctly ascending the base of the 
conidiophore.” As regards the first coil of mycelium, Mr. Plow- 
right writes : “ I distinctly saw this curved in two oospores, and I 
believe the mjmelium comes out with a curl.” The same gentle- 
man, under date May 19, writes: “I saw a great many conidio- 
pliores both with conidia in situ and not ; most conidia had fallen 
off; latterly 1 saw plenty of convoluted bases.” The evidence of 
identity appears complete, and many of the figures here published, 
and others not published, have been confirmed by Messrs. Vize 
and Plowright. 
At Q on Fig. 13 may be seen Peronospora mycelium with a 
young plant (q^) growing from amongst the starch of the potato 
tuber, the dark back ground showing the cell wall corroded by 
the fungus, and at r a similar fragment of mycelium upon the 
cuticle of a potato leaf ; it is very common to see one cell of the 
cuticle thus discoloured by the corrosive mycelium, the corrosion 
of the cell being caused by the mycelium passing over and upon 
it. Both threads here shown come direct from last year’s resting- 
spores. At s is engraved a branch of the potato fungus, showing 
the numerous partitions with which the threads are at times 
furnished, and at t is a typical well-grown branch of the fungus, 
with a full-grown conidiuni at the apex ; this conidium may either 
discharge zoospores, as at u, or an irregular mass of protoplasm, 
as at V, from either of which a new plant may spring, and in this 
habit the conidium agrees well with the resting-spore : the branch 
in this figure is shown as continuous, and though furnished with 
the vesicular swellings no partitions are present, the branches are 
frequently so seen. At w is illustrated a small weak plant, giving 
rise to a branch, which branch is developing into a large and 
strong plant; such a phenomenon is by no means uncommon, 
and shows how the fungus increases itself in every possible way, and 
may, at times, be proliferous. 1 have frequently seen this secondary 
robust thread branched. 
During the last hours of completing this, the last engraving 
(Fig. 13) illustrative 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 secondaiy 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- 
