ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
667 
nucleolo is never present. The nucleus is composed of a hyaloplasm 
enclosing minute granulations of chromatin. Haustoria are present, and 
are as well developed as in the Peronosporese ; they have from two to 
six nuclei. In the pseudoperidium each cell has two nuclei, and the 
same is the case with the basids, the secidiospores, the uredospores, and 
the teleutospores ; four were observed in the uredospores of Uromyces 
Betse. 
In a number of species belonging to various genera, the same authors 
observed a coalescence of the two nuclei of the cells of the teleutospores, 
which they regard as a kind of pseudo-impregnation, a conjugation of 
rudimentary male and female elements similar to what takes place in 
Spirogyra. A similar fusion of nuclei takes place in the aecidiospores. 
This process of pseudo-impregnation is described more in detail in 
the case of Gymnosporangium Sabinse. It consists essentially in the 
fusion of the two nucleoles, which are, in these nuclei, large and sharply 
defined. 
Triphragmium.* * * § — Mr. G. Massee gives a monograph of the known 
species of this genus of Uredinese, and remarks that three forms of spore 
belonging to the teleutospore stage are to be met with in every species, viz. 
a radiately three-celled spore, which is by far the most abundant in 
nearly every species ; a spore composed of two superposed cells, each 
cell having a lateral germ-pore ; and a one-celled spore with lateral 
germ-pore. 
Parasitic Fungi. — In his report for 1892, Prof. J. E. Humphrey j 
describes the fungi which cause the following diseases in cultivated 
plants : — The sclerote disease of cucumbers, by Sclerotinia Libertiana> 
which probably possesses a conidial form of the Botrytis type ; powdery 
mildew by Erysiplne Cichoracearum ; downy mildew by Plasmopora 
cubensis ; damping off by Pythium Be Baryanum ; leaf-blight by Clado- 
sporium cucumerinum ; leaf-glaze by Acremonium sp. ; a violet disease 
by Phyllosticta Violae; black-knot of the plum, by PlowrigJitia morbosa ; 
powdery mildew of the strawberry by Sphserotheca Castagnei ; powdery 
mildew of the gooseberry by S. moro-uvse ; cluster-cup of the gooseberry 
by AEcidium Grossularise ; a disease of the hazel, by Cryptosporella 
anomala. 
Herr D. IwanowskyJ finds the tobacco-plant in cultivation to be 
subject to two diseases, one due to the attacks of Oidiurn Tabaci , the 
other to bacteria. 
M. E. Prillieux § describes a disease which attacks the endive, caused 
by the sclerotes of a fungus nearly allied to Sclerotinia Libertiana. 
According to Prof. J. C. Arthur and Miss K. E. Golden, || the sugar- 
beet-root is liable to two parasitic diseases, one due to a bacterium, the 
other to a fungus, Oospora scabies , identical with that which produces 
scab in the potato. 
* Grevillea, xxi. (1893) pp. 100-19 (7 figs.). 
f Rep. Massachusetts State Agric. Exp.-Stat., 1892, 39 pp. and 5 pis. Cf. this 
Journal, 1892, p. 831. 
t Land. u. Forstwirthsch., 1892. See Bot. Centralbl., 1893, Beih., p. 266. 
§ Comptes Kendus, cxvi. (1893) pp. 532-4. 
|| Bull. Purdue Univ. Agric. Exp. Stat., id. (1892) pp. 54-62 (1 pi.). 
