40 
PROGRESS OF MICROSCOPICAL SCIENCE. 
and physiological observations. The previous literature of the subject 
appears to have been exhaustively worked up. Commencing with 
Pilobolus, the various genera containing fimicolous species are passed 
in review; those in countries other than Denmark are also enumerated. 
There are twelve species of Agaricus, and the same number of Co- 
primes. Coprimes niveus is treated in detail, and the development and 
structure of its sclerotia described. The latter are exceedingly vari- 
able in size, form, and colour ; they possess a fine grey membrane on 
the outside which appears under the microscope as a granular mass 
composed of broken-down cells ; beneath this is a black cortical por- 
tion in continuation with the former, and composed of many irregular 
rows of small thick-walled cells. This tissue passes gradually into 
the central portion made up of a pseudo-parenchyma with fine meshes, 
the intervals filled with air. The cells of this tissue are very irre- 
gular, and become gradually larger towards the centre ; if the sclero- 
tium be boiled with potash they are seen to form irregular cylinders 
branched and provided with numerous partitions ; these interlace and 
form a firm, very close tissue. A dimorphism is noted in this species : 
in one form the pilous is covered with a felt-like, white, floccose down, 
and in the other with a snow-white, floury stratum ; the first form 
develops solely from the sclerotium, the second never. 
Microscopic Characters of a New Order of Algce. — Mr. S. Moore 
gives an abstract of a work by Y. B. Wittrock, of Upsnla, on this sub- 
ject (1877 ) in the ‘Journal of Botany J for June. One of the principal 
characters of this order, represented by the single genus Pithophora, is 
a branched thallus, the branches taking origin from the upper part of 
the mother-cell at a short distance below its top. On examining an 
individual, one secs that it consists of two regions, a unicellular 
usually unbranched basal portion (the “rliizoid” part), and a multi- 
cellular usually branched “eauloid” part. Bamification of this cauloid 
part is often various in degree in the same species. In P. Sumairana 
the branches are of the first degree only ; in five other species 
(P. Kewensis, cequalis, polymorpha, Cleveana, Zelleri) eitlxer of the first 
or second degree (and sometimes opposite in the last two) ; while in 
P. Boettleri a third degree of ramification is met with, the branches of 
the first degree being placed three (sometimes four) in a whorl, hut 
those of the second and third either singly or in pairs. The cells 
which bear these branches are either ordinary cells or spores, rarely 
“ subsporal ” cells (to be spoken of presently). The lateral branches, 
which are most usually single, have a tendency to grow on one side, 
but occasionally other (“ accessorial ”) branches are found taking 
origin, not from a point near the top, but from some other part, often 
near the base, of the mother-cell. The rhizoid part consists, as has 
already been mentioned, in most cases of a single unbranched cell, 
though sometimes several-celled rhizoid parts are met with, and in 
two of the species these can occasionally produce spores. On the 
other hand, the rhizoid part is sometimes not even composed of a 
whole cell, and only appears in the form of a basal protuberance from 
the mother-spores; while in P. Cleveana it is occasionally not de- 
veloped at all. The anatomical elements consist of vegetative cells 
