ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 95 



of these hypliae perform tlie function of conducting cells, and the 

 spherical body becomes an ascus, in which eight ascospores with 

 double cell-walls are formed. The ascus is either quite solitary, or 

 as many as four, with their conducting cells, stand at the same height 

 on the mycelial filaments. The author classes Eremascus among the 

 Gymnoascacese. 



A new species of Gymnoascus is described, G. setosus, found in 

 quantities on a wasp's nest. 



The author nest gives a full description of the history of develop- 

 ment of a species of Sterigmatocystis, which forms both conidiophores 

 and asci in a very peculiar way. The perithecia are buried in a large 

 hollow envelope formed of branched filaments, the ends of which swell 

 up into colourless or slightly yellow thick-walled vesicles. Within 

 this cushion are produced the asci. Two very fine hyphee swell up 

 at their apices, coil, one forming the " nucleus," the other branching 

 and forming the wall of the perithecium. The young fructification 

 has the remarkable property of its colourless contents turning a 

 beautiful blue on addition of ammonia or potash, which changes to 

 red when an acid is added. This colouring substance occurs only in 

 the wall of the perithecium, which, when ripe, is nearly black, and 

 in the ascospores, which are purple. These latter ripen very slowly, 

 and, on germination, produce again the conidiophores of Sterigmato- 

 cystis. 



In Chcetomium (0. Kunzeanum Zopf) the origin of the fructifica- 

 tion is a single thickish hypha which developes into a distinctly 

 segmented spiral. In the further development Eidam agrees with 

 Van Tieghem rather than with Zopf. A pseudo-parenchymatous ball 

 is formed by the branching of a single spiral filament which is clearly 

 distinguishable from the rest of the mycelium. 



Conidia of Peroiiospora.* — M. Coruu gives a more exact descrip- 

 tion than any previous observer of the mode of abstriction of the 

 conidia of Peronospora. In the middle of the septum which separates 

 the conidium from its hypha is formed a soluble gelatinous layer. 

 This accounts for the rapid development of Peronospora after rainy 

 weather. Oornu disputes the possibility of the oospore directly pro- 

 ducing zoospores on germination like the conidia, or rather the 

 sporangium, as de Bary has described in the case of Cystopus. Each 

 oospore, on the contrary, developes into a mycelial filament bearing 

 a sporangium. Their germination depends greatly on moisture and 

 temperature, as also on the depth at which they are buried in the 

 soil. When at a considerable depth they may retain their power of 

 germination for from two to five years. 



Pleospora herbarum.t— Great confusion has resulted from authors 

 having described under this name different organisms which have no 

 genetic connection with one another. F. G. Kohl has carefully 

 investigated its life-history, having sown the ascospores obtained from 



* Cornu, M., ' Etudes sur les Peronosporees. II. Le Peronospora des vignes.' 

 91 pp., 5 pis., Paris, 1882. See Bot. CentralbL, xv. (1883) p. 274. 

 t Bot. Oentralbl., xvi. (1883) pp. 26-31. 



