PROGRESS OF MICROSCOPICAL SCIENCE. 45 
and become indistinguishable from the filaments derived from spores 
attached to the outside. The diameter of the largest canals containing 
filaments in which there is occasionally a doubtful dissepiment, and 
which flourish in the organic matter between the lamin of a septum, 
is ;45 inch; that of the typical and ordinary tubes is from ;31,, to 
agp inch; and the finest tubes are as small as 55}5, inch in diameter. 
The canals and included filaments in some instances increase in 
calibre at certain spots, and even form globular expansions, but 
usually the same diameter is retained ; the enlarged portions relate to 
the reproductive process. The cell-wall of the filament is in close 
contact with the sclerenchyma of its canal. In a littoral species 
(Caryophyllia Smithi) the parasite is identical with Saprolegnia feraz, 
Ktz.; but there is a manifest distinction between it and those of the 
other forms. The parasite of the littoral coral greatly resembles 
those of the shells of Mollusca and of the scales of fish. Although it is 
quite possible that all the parasites of the corals described may be 
referred to one species, their type being altered by the peculiar con- 
ditions surrounding them, still it is thought advisable to regard them 
as members of two species. The classificatory position of the parasites 
is in the midst of a group of forms which have complicated life-cycles, 
such as the Achlyans (proper), the Saprolegnie and Empusine and 
Botritide, and the filamentous false-root bearing genera Codium and 
Bryopsis—forms which are more or less the expressions of one or- 
ganism under different conditions and age. 
Phallus fetidus. — Mr. Meehan exhibited to the Phil. Acad. of 
Science, at its meeting in October last, specimens of what he supposed 
to be a variety of this fungus. It was very rare with him, the last 
time it had appeared on his grounds was seven years ago. Its brilliant 
scarlet colour and strong fetid odour would have attracted attention 
had it been in existence during that time. It was doubtful if any 
existed in the vicinity, and it was an interesting question whether the 
spores or mycelium had been in the ground all that while, or whether 
it had been recently brought as a spore in the atmosphere. But the 
main point he wished to draw attention to was the attraction the fetid 
plant had for meat flies. They abounded on the plants. The common 
toad plant of greenhouses (Stapelia variegata) attracted these in the 
same way, and it was said to be a scheme to aid the plant in cross 
fertilization, the stench attracting the flies, and inducing them to 
deposit eggs, under the impression that it was rotten meat; though 
what benefit it was to the fly to be thus fooled had never been made 
clear to him. In the case of this fungus, however, it would hardly be 
contended that the flies had been deceived for the purposes of fer- 
tilization, nor could he understand why “ in-and-in breeding,” if bad 
for phenogams, should not be injurious to a fungus as well. 
The Structure of Precious OpalAt a recent meeting of the 
Academy of Science of Philadelphia, Professor Leidy stated that 
Signor A. G. Arevalo, proprietor of one of the opal mines in Queretaro, 
Mexico, had recently called upon him, and exhibited a large collec- 
tion of cut opals of various kinds, comprising the milk-white opal 
with a rich harlequin display of colours, the less valued transparent 
glassy variety with rich hues, and the red fire opal of different shades, 
