845 DR. W. R. MSNAB. 
definite unicellular fungus, and described the formation of 
ascospores. He, however, incorrectly stated that yeast- 
like cells could be produced from Mucor racemosus and M, 
Mucedo. Cohn has recently shown that there is no proof 
whatever that Penicillium and Bacteria have any connection, 
Indeed, the strange results mentioned above by so many 
different authors nearly all proceed from imperfect observa- 
tions and a misapplication of the facts of pleomorphism. 
I. Asexual Reproduction of Penicillium by Conidia. 
The conidia or asexually produced spores of Penicillium 
are very minute, and measure only 0:0025 mm. Mag- 
nified 300 diameters, they appear to the eye as small 
round points with strongly shaded margins, like the fine 
particles in a fluid which has been frequently filtered 
but is still turbid. ‘The highest magnifying powers 
afford no means of giving a better description. No contents 
are observable, no membrane can be seen surrounding 
them, and the outer surface shows no _ irregularities. 
Turn them as you please, the mark of the points of attach- 
ment cannot be detected; they show, however, so many varia- 
tions from the spherical form that they can hardly be called 
round. 
If a single spore be placed in a clear solution of an 
organic substance remarkable changes immediately com- 
mence. The spore swells up considerably and regularly 
in all directions. Now, for the first time, the contents 
become visible, and the delicate smooth membrane sur- 
rounding them. ‘The contents consist of very finely granular 
protoplasm, which appears to fill the cell uniformly. By 
very careful adjustment one or more very minute vacuoles 
may be brought into view, which in general do not fuse 
together to form a large one. ‘The swelling of the spore 
does not exceed three times that of the unaltered one, 
and at this stage germination takes place, sometimes 
one, sometimes two to six, projections forming in dif- 
ferent directions. These are always narrower than the 
swollen spore, which renders them easy to recognize, even 
at the first glance. ‘The projections are so regular in 
width that they look as if formed to pattern. Growth occurs, 
apparently, only at the apex of the hypha to which the 
projection gives rise. The hyphz soon cease to be unicel- 
lular, transverse septa forming at irregular distances from 
the apex. It is now possible to distinguish the terminal 
cells from the rest, since the end-cell alone grows in length, 
a subsequent intercalary extension of the cells of the hyphe 
