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part, which slips out from the older, must he somewhat smaller. Inside of 
the box is a membrane, inclosing the internal coloured or colourless sub- 
stance, imbedded in which may always be seen, at least in the larger forms, 
a distinct nucleus, sometimes two, and sometimes a “germinal dot,” with 
numerous fine threads radiating from the nucleus, or the germinal dot. As 
the frustule increases in width, one portion slips out from the other, and 
sometimes successive additions of siliceous matter are made to the edges 
of the box, somewhat analogous to the successive additions to the edge of 
the shell of a mollusc. When the widening of the frustule has reached a 
certain extent, the lining membrane, at the places which would be exposed 
if the two portions were wholly to slip apart, infolds. He has reason to 
believe that, previous to this, a double membrane of extreme tenuity has 
been formed, commencing its growth at the nucleus (which itself is divided), 
and extended to the margins of the cell, which is thus divided into two 
nearly equal parts ; for, as soon as this infolding commences (perhaps now 
accelerated by the admission of water), the line of division can be seen 
progressing steadily inwards by the parting of this thin double membrane, 
so that in fifteen or twenty minutes the fissure is complete. He has, in very 
large Pinnularice, witnessed the whole phenomenon, from its inception up 
to the final self-division. While the fissure occurs in the short period of 
time he has named, to complete the self -division requires about six days. 
Is there Alternation of Generations in Fungi. — Mr. M. C. Cook, M.A., 
believes that it is questionable whether this phenomena occurs in fungi, as 
Professor (Ersted alleges. He thinks it takes place in the same plant, as in 
the case of Bunt ; but he feels great difficulty in believing in this process, 
where the generations were passed in different plants, until confirmed by 
other observers. If the spores of Acidium Berleridis were taken from the 
barberry and sown upon young wheat plants, and all these plants became 
infected with corn mildew ( Puccinia graminis ), to which wheat is but too 
prone, it certainly seemed premature to say that the spores of the Acidium 
caused the Puccinia to be developed as a second generation ; whereas it is 
much more probable that the germs of the mildew already lay dormant in 
the wheat, and, at most, the sowing and growing of the Acidium spores only 
stimulated the mildew to a more rapid development. 
Altering the Name of a Bog-moss. — Dr. Braithwaite is sufficiently conscien- 
tious in giving a new name to a species. In his last paper in the “Monthly 
Misroscopical Journal,” June, he gives the following observations on this 
subject. In Phsenogamic Botany, Entomology, and other departments of 
natural history, the adoption of the first name by which a species has been 
described (dating from the establishment of the binomial nomenclature by 
Linnaeus) is considered imperative; yet the synonymy of mosses is wofully 
confused, for Hedwig and others gave a new specific name as often as they 
changed the genus — a rule not sanctioned by the best authorities. Others 
may object with greater reason that the brief discriptions of the older 
authors are not sufficient to identify the species with certainty, yet it must 
be remembered that the actual specimens of very many of them are in 
existence, and their examination by a competent authority in most cases 
settles the question. Prof. Lindberg, who has worked so indefatigably at 
this unattractive department of botanical literature, has shown, in his “ Bev. 
