316 PODISOMA MACROPUS, 
and placing it under the field of a microscope, I fóund it to 
consist entirely of immense numbers of minute fungi allied 
to the genus Puccinia, characterized by a slender filament or 
pedicle, on the summit of which are two cells of the form 
represented in the adjoining figure. Each cellis of a trian- 
gular form, the two being united at their, bases. Internally 
these cells are filled with yellowish green granules, besides 
which there exists a transparent spherical body, which I sup- 
pose to be a nucleus or cytoblast. The accompanying figures 
will give you a better idea of the fungus than any verbal 
description. The existence of two distinct cells is easily 
demonstrated by macerating the specimen for a short time in 
water, when they readily separate from each other, and in 
some instances I have noticed the projection ofa tube not 
unlike a fallen tube, from one of the angles. I have made 
numerous searches for these parasites, but have almost never 
detected them, except in the localities above mentioned, viz : 
the tufts composed of acerose leaves and the * Cedar apple.” 
The tufts with acerose leaves are not identical as I believe, 
with the variety of form which occurs in the young shoots of 
the J. virginiana, described in Bigelow's Med. Botany and 
by yourself in the Flora Boreal. Americana, also in the 
description of the J. burmudiana in Lond. Journ. of Botany 
for March 1843. The form of the leaf is in both cases 
acerose, but the tuft to which I refer, forms a single dense 
spherical mass, the twigs so crowded together as scarcely to 
allow the light to pass through, looking at a distance like the 
nest of some bird. These masses vary in size from that of 
the first to eighteen inches in diameter. Generally not more 
than one mass is seen on the same tree, sometimes, however 
two or three. I have never seen a single tuft like those described 
in which the fungus in question was not present, and this is the 
result of a great number of observations. 
The “ Cedar apple,” is an excrescence of the bark of the 
J. virginiana, and usually attributed to the presence of the 
ova of insects. On its surface are generally to be seen $ 
depressions from which at certain periods there projects à 
