the same name. On the Garden Pea its effects are so injurious
as sometimes to destroy the whole crop. That it should
occasion so much mischief, ceases to he wonderful, when we
submit it to the power of the microscope. The leaves are
then found to be completely coated (sometimes on both sides)
with a thin hut very dense web of filaments, which must materially
interrupt the natural functions of the plant. Added
to this, it is highly probable that the innumerable receptacles
or sporangia situated on the filaments, derive their support in
a greater or less degree through their medium from the juices
of the plant. These parasites have been discovered on a great
number of vegetables; and at present it is extremely difficult
to say what are distinct species. I have recently been informed,
however, by my friend Dr M o u g e o t , that M . W a l l -
ROTH has wi-itten an essay on this genus, to which he has
given the name of Alphitomorpha; he reduces the number of
species to fifteen, and rejects all names taken from those of the
plants on which they grow.
I have represented one of the sporangia dehiscent in the
plate; hut do not affirm it to be naturally so. Such minute
subjects are difficult to dissect; and it is probable I may not
be correct in this representation.
Fig. 1. E. Pisi, nat. size. Fig. 2. A group detached. Fig. 3. The same.
Fig. 4. Sporangia very highly magnijied. Fig. 5. Sporidia.— AU magnifie
d except Fig. 1.