LIFE-HISTORY OF PENICILLIUM, 857 
present. The object is far too small to permit the whole 
process of spore-formation to be observed, but there can be 
little doubt that the process is similar to that observed by 
De Bary in Eurotium, and by Janczewski in Ascobolus. 
Darkening of the margins of the young spores indicates the 
formation of the cell-wall, and when the ascus is fully 
developed it contains eight spores, without any trace of pro- 
toplasm remaining unused (Plate XVIII, fig. 9). 
When the spores are ripe the string of asci breaks up, 
and only the little stalklet of the branch remains attached to 
the main axis (Plate XVIII, fig. 10). 
In the sclerotium (sporocarp), therefore, we have the 
carpogonium-hyphe developing two morphologically and 
physiologically distinct elements; the one developing the 
asci and ascospores, the other serving as nutrient organs and 
taking up nourishment from the substance of the sclerotium 
itself. During the consumption of the sterile tissue of the 
sclerotium crystals are formed near the margins of the parts 
being destroyed. ‘These crystals consist of calcium oxalate 
and often form regular octohedra (Plate X VIII, fig. 7e). This 
formation of erystals of calcium oxalate is of the same physio- 
logical importance as the formation of similar crystals in the 
higher plants. 
The consumption of the sterile tissue keeps pace with the 
development in the interior of the sclerotium, being remark- 
ably slow for a fungus. It may take entire weeks to observe 
any progress. As the asciferous hyphe spread from the 
centre by the growth of the numerous apices of the threads 
spores are developed in regular succession. ‘Then as the 
asci ripen they fall off and the spores are set free by the dis- 
appearance of their walls (Plate XVIII, fig.7/f). After the 
germination of the sclerotium spores may be observed in its 
central part in from four to six weeks, while the last-formed 
asci in the periphery only form ripe spores about five months 
afterwards. 
At last the sterile tissue of the sclerotium is reduced to a 
mere wall two or three cells thick, of small, slightly elongated 
cells of a brown colour. The cortex of brown cells, which 
are partly corky in composition, remains undissolved, and 
serves as a firm investing-capsule. When all the nutrient 
substance is absorbed all the hyphe and asci which were 
near the margin disappear, as they had done in the 
earlier stages in the centre, and there remains now only 
a mass of spores, intermixed with crystals of calcium oxa- 
late, and surrounded by the firm yellow-brown capsule. 
When the capsule becomes dry, in the course of time it 
