352 DR. W. R. MSNAB, 
stage, before the formation of any conidia was noticed, the 
bread was placed between two glass plates to prevent the 
access of oxygen and the formation of the ordinary coni- 
duferous condition of Penicillium. 
The sclerotia began to appear on the seventh day, and were 
easily observed with a lens magnifying twenty diameters as 
white spots. As the youngest stages could not be so readily 
observed, thin slices were made and coloured with aniline, 
which brought out the young sclerotia very distinctly. The 
earliest observed stage that could be distinguished was a 
spirally-twisted structure, seated on a thick short-celled 
hypha. The spirals consist clearly of two different cells 
which are thicker than ordinary mycelium, and_ their 
apices incline towards each other after having twisted 
one to one and a half times in opposite directions. These 
we must consider to be the carpogonium and the an- 
theridium. Shortly after the entwining of these cells (the 
sexual organs), which much resemble those of Gymnoas- 
cus, one part of the spiral, which we must consider to 
be the carpogonium, begins to grow as a consequence 
of fertilization, and to form tube-lke projections which in 
their diameter and contents resemble the mother-cell. At 
the same time the hypha on which the reproductive organs 
are placed begins to form numerous branches (Plate 
XVII, figs. 2and 3). The growth of theseis very rapid, and 
the whole carpogonium is surrounded and enclosed by them. 
‘The whole now appears as a mass of threads, even when ren- 
dered transparent with glycerine, ammonia, or caustic potash. 
At the time the carpogonium became imbedded in sterile 
hyphe it had already begun to form branches. A section 
of the young sclerotium (sporocarp) shows the carpogonium 
as a branched mass in the centre of the sterile hyphe 
(Plate XVII, fig. 1) ; it (fig. 1 @) can at once bejdistinguished 
by the size of its hyphe. The sterile hyphe (fig. 1 6) have 
only a diameter of from 0:0030 to 0:0040 mm.; they are 
copiously and irregularly branched, and are constantly 
changing their direction, their septa being also very numerous. 
The carpogonium-hyphee, on the other hand, are nearly twice 
as thick, being from 0:0050 to 0:0070 mm. in diameter; 
septa are absent, and the arrangement more regular. The 
hyphe of the carpogonium as they grow interpenetrate be- 
tween the sterile hyphe. Outside the carpogonium-threads 
there are from eight to sixteen layers of these, varying in 
number according to the vigour of the plant. Outside the 
sterile hyphe numerous hyphe (fig. 1 c) are seen, which 
probably belong to the neighbouring mycelium. 
