ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
447 
Reproduction in the Phycomycetes.* — M. P. A. Dangeard reviews 
the various theories with regard to the mode of reproduction in the 
Phycomycetes or Siphomycetes (Cliytridiaceae, Saprolegniaceae, and 
Mucorini), agreeing in the main with those of Trow j and Humphrey,^ 
while he differs in some important points from those of Hartog.§ The 
act of fecundation is preceded by the disappearance of the greater part 
of the nuclei, two only remaining, which coalesce into a single sexual 
nucleus. The nucleus of the Saprolegniaceae is composed of a nuclear 
membrane enclosing hyaloplasm, in the centre of which is a nucleole. 
The vacuoles which are seen in the oosporange cannot be regarded as 
nuclei in various stages of conjugation. The antherids are, like the 
oogones, multinucleated. At the moment of germination the oosperms 
contain several nuclei in the protoplasmic layer which extends from the 
central oily globule to the cell-wall. Whether these are old nuclei 
previously concealed in the protoplasm, or whether they result from the 
division of a single nucleus, i£ uncertain. Oosperms may be formed 
parthenogenetically ( Saprolegnia Thureti ), and then contain only a single 
nucleus. There are still important points undecided with regard to the 
mode of fecundation in the Mucorini. 
Basidiobolus.|| — Herr M. Raciborski points out that the Phycomycetes 
are composed of two sharply distinguished series. In one of these, the 
Siphomycetes, including the Mucorini, Peronosporeae, and Entomo- 
phthoreae, the organism consists, in the vegetative condition, as in the 
Siphoneae, of unseptated multinucleated tubes. In the other series, to 
which belong most of the Chytridiaceae, and which he calls the Archi- 
myoetes, the vegetative structure is composed of normal uninucleated 
cells, resembling those of the Conjugatae. Basidiobolus belongs to the 
latter of these groups, being made up of unicellular structures, which 
form a colony of cells but slightly connected with one another. 
In Basidiobolus, as in the Conjugatae, the process of impregnation 
divides itself into two stages, which may be widely separated in point of 
time — the fusion of the protoplasmic contents of two cells, and the fusion 
of the two sexual nuclei. The interval between these two processes may 
extend to some weeks ; the second process may be promoted or delayed 
by external conditions. 
The author gives details of the results of the changes caused in 
Basidiobolus ranarum by growth in different nutrient media. The best 
medium is a peptone solution. By changing the composition of the 
medium, the fungus may be induced to pass into a palmella condition 
similar to that of some algae, which leads to the formation of perfectly 
free unicellular individuals. 
Hypostomacese, a new Family of Parasitic Fungi.1T — Under this 
name M. P. Yuillemin establishes a new family of Ustilagineae, composed 
of the genera Meria and Hypostomum, intermediate between the Asco- 
mycetes and the Hypliomycetes. The author regards it as the point of 
departure of a series distinguished by a progressive adaptation to 
parasitic habits and degradation of the reproductive organs. 
* Le Botaniste (Dangeard), iv. (1896) pp. 249-56. Cf. this Journal, 1894, p. 701. 
t Cf. this Journal, aide, p. 216. X Cf. this Journal, 1893, p. 764. 
§ Cf. this Journal, ante, p. 335. || Flora, lxxxii. (1896) pp. 107-32 (11 figs.). 
If Comptcs Rendus, cxxii. (1896) pp. 545-8. 
