ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
381 
subsequently indistinct, and the young oospheres contain scarcely a trace 
of nucleus. In S. monoica the antherids possess several nuclei. In 
Aphanomyces, the number of nuclei in the oogone is about fifteen, in the 
antherids from three to six. In Pythium, the number in the oogone is 
from five to fifteen, according to the species, and it is possible to follow 
them out until the formation of the oospheres. In Cystopus the oogone 
has a large number of small nuclei ; in Plasmopora densa both oogones 
and antherids are plurinucleated. As a general rule it may be said that 
both oogones and antherids contain several nuclei ; those of the oogone 
may be divided into two groups ; some of them are located in the peri- 
plasm, and are utilized in the formation of the spore-membranes ; others 
remain in the oosphere ; at the moment of fecundation they become 
indistinct, or only two of them are visible towards the centre ; subse- 
quently a large number are formed, which furnish, by division, the 
nuclei of the zoospores and of the vegetative filaments. A similar 
process appears to take place in the antherids. 
Action of Fungi on copper and bronze.* — M. R. Dubois finds that 
concentrated solutions of cupric sulphate, neutralized by ammonia, as 
employed for the immersion of gelatinized plates used in photogravure, 
frequently contain whitish flocks of a septated fungus-mycele closely 
resembling that of Penicillium or Aspergillus. If a solution of cupric 
sulphate containing this mycele is placed on a carefully washed bronze 
coin, it will, when the liquid is completely evaporated, be covered by 
green spots resulting from the power of the fungus-mycele to convert 
the cupric sulphate into carbonate. 
Effect of corrosive sublimate on Fungi.j — According to Mr. H. W. 
Russell glycerin containing 1 part in 10,000 of mercuric chloride does 
not interfere with the growth of Penicillium glaucum , while a proportion 
of 1 part in 6000 or 1 in 4500 entirely stops it. This fungus appears 
to be somewhat less resistant to the poison than some other forms. 
Structure of the Peronosporese.J — M. L. Mangin contests the view 
that the substance known as fungin or metacellulose exists as a distinct 
ingredient in the cell-wall of Fungi. The structure of the cell-wall in 
Fungi is complex, and varies greatly in the different families. In the 
Peronosporeas, it consists, in the mycele and oosperms, of two substances, 
cellulose and callose, which can be separated by the method previously 
described by the author.§ The callose may occur in the form of 
spherical masses, or of rings on the inner side of the tube, sometimes 
almost completely closing its cavity. The mycele of the Peronosporese 
is readily distinguished from that of other families of parasitic Fungi by 
the presence of these thickenings of callose ; the appearance resembles 
that sometimes presented by pollen-tubes. The mycele of these fungi 
also puts out small haustoria, of variable form, which furnish excellent 
characters for distinguishing the species; these also consist partly of 
callose, which is sometimes present in very large quantities. The 
constant presence of callose in the mycele of the PeronosporeaB serves as 
a test for the least trace of these parasites in the plants which they infest. 
* Comptes Rendus, cxi. (1890) pp. 655-7. 
f Bot. Gazette, xv. (1890) pp. 211-2. 
i Comptes Rendus, cxi. (1890) pp. 923-6. § Of. this Journal, 1890, p. 735. 
1891. 2 d 
