LIFE-HISTORY of PENICILLIUM. 351 
lium placed on the under surface. Water from a wash- 
bottle was then directed on the spots where the spores 
were, in order to render the bread moist and to force the 
spores more into the interior. When so treated the bread 
was placed with the spores downwards on a flat surface, and 
the whole was carefully covered over. After about three 
weeks the blue-coated bread was lifted, and on the under side, 
here and there among the vigorous white mycelium, small 
protuberances were observed, more or less aggregated in 
little heaps. ‘They could be readily separated from the 
white mycelium, and then appeared as solid hard bodies, 
not quite round in form, and resembling yellow grains of 
sand in size and colour. Internally they consist of a uormally 
formed, colourless tissue of thick-walled cells, which are best 
seen in thin cross-sections. ‘The tissue possesses all the 
characters of vegetable cellulose, the thickness of the walls 
indicating that the part was in a resting stage (Plate XVII, 
fig. 5). In all probability this plant could be no other than 
Penicillium itself, as other fungi were believed to be ex- 
cluded. New experiments, which were quickly repeated in 
the same manner, confirmed the results and showed that 
Penicillium had a sclerotium-form like many other fungi. 
Several questions now arose for solution, such as—How was 
this body formed? Was it the result of sexual generation ? 
What was its physiological signification? what would be 
developed from it? and could it be clearly demonstrated that 
it belonged to Penicillium ? 
Sclerotia of Penicillium had been already described by 
J. H. Leveillé! in 1840. He observed small yellow bodies, 
which he took for sclerotia, on very old tamarinds, on which 
Penicillium was growing; but he does not seem to have 
paid much attention to them. ‘To Brefeld, therefore, is un- 
doubtedly due the credit of having pointed out the true 
relation of this structure to Penicillium. 
Brefeld placed Penicillium-spores in the manner already 
mentioned on both sides of a flat piece of fresh bread half 
an inch in thickness, and let a few drops of distilled water 
fall on it and be absorbed. On the third day the piece of 
bread, which was lying free under a bell-glass, was gently 
nioistened, and on the following days well watered witha wash- 
bottle. From the sixth to the seventh day, according to the 
temperature, the development of the mycelium was so ener- 
getic that the temperature of the air in the bell-glass was 
raised, while that of the bread reached 111° F. At this 
1 «Sur les Sclerotium,” ‘ Annales des Sciences Naturelles,’ (2° série), 
tome xx, 1843. 
VOL, XV.—-NEW SER, AA 
