ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
365 
(the term given by Schmitz to the entire fertile tissue of a single cysto- 
carp which has resulted from the development of a single impregnated 
initial cell, whether this cell be an impregnated oosphere or an impreg- 
nated auxiliary cell). In all three this oosphere forms branched threads 
which expand within a definite section of the fertile shoot along the 
central axis, and then put out numerous short lateral axes, radiating on 
all sides and projecting outwards. In all of them the terminal cells of 
these lateral axes congregate into a more or less dense peripheral 
hymenium, permeated by numerous paraphyses, and develope succes- 
sively into carpospores. The differences between the three genera lie 
in the structure of the thallus, and in the special form of the cystocarp. 
In particular the cystocarp of Naccaria is much more complicated in 
structure than that of Atractophora. 
Algge which perforate calcareous shells.* — MM. E. Bornet and 
C. Flahault give a monograph of the species of algge known to inhabit 
the shells of molluscs and other calcareous substances in the sea, or less 
often in fresh water. The species described are : — Gomontia polyrliiza, 
SipJionocladus voluticola^ Zygomitus reticulatus sp. n., Ostreohium Quehetii 
n. sp., Mastigocoleus testarum, Plectonema terebrans sp. n., Phormidium 
incrustatum, Hyella csespitosa, Lithopythium gangliiforme sp. n., and 
Ostracohlahe implexa sp. n. Of these the last two are probably Fungi ; 
all the rest belong eitlier to the Chlorosporese or the Phycochromaceae. 
All the species present the same general mode of development. At first 
they expand horizontally in the epidermal layer of the shell, either in 
the form of an irregular network, or radiating from a central point. 
From this layer proceed branches which penetrate vertically into the 
test, and others which elongate parallel to the original ones, finally 
becoming so numerous that the calcareous substance entirely disappears, 
when they become exposed and produce abundantly their reproductive 
cells. 
The preparations were in all cases made by first removing the 
calcareous substance by means of Perenyi’s fluid — 4 volumes of 10 per 
cent, nitric acid, 3 volumes of alcohol, and 3 volumes of 0*5 per cent, 
chromic acid. 
Ecklonia.l — Dr. G. B. De Toni gives a monograph of this boreal and 
Australasian genus of Phaeosporeae, with a description of each of the six 
known species, and of its geographical distribution. 
Spines of Xanthidium.t — Herr F. Elfving finds that the spines of 
Xanthidium aculeatum originate as hollow protuberances, and cannot 
therefore be formed by apposition. 
Apiocystis.§ — Mr. S. Le M. Moore describes the life-history of Apio- 
cystis Brauniana, found growing on Cladophora and Mesocarpus. In its 
earliest condition it consists of a colourless sac containing a single gonid, 
from the distal end of which proceed two cilia, which pierce the wall of 
the parent-cell and extend some distance into the surrounding water. 
This gonid divides by a number of successive bipartitions, the original 
*■ Bull. Soc. Bot. France, sxxvi. (1889.) Actes du Congres de Bot., pp. cxlvii.- 
clxxvi. (7 pis.). 
t Notarisia, iv. (1889) pp. 782-90. J Bot. Notiser, 1889, pp. 208-9. 
§ Journ. Linn. Soc. (Bot.), xxv. (1890) pp. 362-80 (3 pis.). 
