ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
765 
at intervals, marking them off into segments, and comprises the genera 
Leptomitus and Apodaclilya. The cellulin- granules of Pringsheim, 
which have not been recognized elsewhere, occur as discoid or lobed 
bodies in both the hyphse and reproductive organs, and are probably a 
soluble form of cellulose available for use in forming and repairing 
cellulose walls. In most of the genera the zoospores display the pheno- 
menon of “ diplanetism ” or double swarming, though this is not uni- 
versally the case; the object of the first swarming is the escape of the 
zoospores from the sporange, that of the second, distribution of the spores, 
to enable them to reach new sources of food-supply. In Saprolegnia and 
Aclilya the zoospores sometimes become encysted within the sporange ; 
in Aplanes both swarming stages are suppressed. Many species pro- 
duce also chlamydospores. With the exception of the newly discovered 
Apodaclilya (?) completa , none of the Leptomiteae are known to produce 
sexual organs of reproduction. Both the young oogones and the antherids 
contain a number of nuclei. Useful methods of culture are described. 
New Chytridiacese.* — Under the name Lagenidium (?) ellipticum 
M. E. De Wildeman describes a new species belonging to the Chytri- 
diaceae, parasitic on the rhizoids of mosses; also another new species, 
Bhizophidium marinum , parasitic on diatoms of the genus Melosira. A 
monograph of the known species of Lagenidium is appended ; and an 
account of all the Chytridiaceae and Protomycetes parasitic on the tissues 
of roots. These include a new genus Asterocystis, near to Olpidium , 
characterized by the cells being elliptical or rounded, and furnished 
with projections which give them a star-like appearance ; and the fol- 
lowing new species — Olpidium Borzii , on roots of Brassica oleracea 
and Capsella bursa-pastoris ; Asterocystis radicis , on a variety of roots ; 
Pleotrachelus radicis, on roots of Tlilaspi arvense. 
Ulocodium and Nemacola.f — According to Sig. A. Jatta, these two 
genera of Lichens established by Massalongo, must be suppressed. 
Ulocodium odoratum is an undescribed species of Biatorina which he 
names B. cohabitans, and with which Ghroolepus odoratum is closely asso- 
ciated, but not organically. Nemacola criniformis is nothing but a form 
of Collema tenax associated with Microcolcus terrestris. 
Nucleus of the Yeast-cell. J — Prof. Fr. A. Jannsens has examined 
the following yeasts, and found therein a nucleus : — Saccharomyces Lud- 
wigii Hansen, S. cerevisise 1 Hansen, S. pastorianus 1 Hansen, Carlsberg 
bottom yeast No. 1 , a top yeast, and a baker’s yeast. 
Especial attention was turned to S. cerevisise 1 and S. Ludwigii , the 
latter having points of especial interest. When the cells are still very 
young and are met with in the resting and vigorous condition, the fol- 
lowing structure of the nucleus can be made out. The nucleus has a 
membrane, and contains a nucleole. The nucleole, which is usually 
spherical and homogeneous, is nearly always found about the middle of 
the nucleus, and occupies about a third of its diameter. The nucleus 
* Ann. Soc. Beige Microscopie, xvii. (1893) pp. 1-32 (3 pis.), 
f Malpighia, vii. (1893) pp. 192-201 (1 pi.). 
% Centralbl. f. Bakteriol. u. Parasitenk. , xiii. (1893) pp. 639-42. Cf. this 
Journal, ante, p. 509. 
3 g 2 
