146 BETTS : THE FUNGI OF THE BEE-HIVE. 
On honey agar on two occasions sclerotia were produced. They 
are irregularly globose sulphur-yellow bodies, 1-2 mm. in diameter ; 
and were crowded together at the foot of the agar slope. Each con- 
sisted of a tangle of numerous thick-walled cells, 12-30 » in diameter 
(average 20-25 p; some large oval ones to 40 x 35 #1; See Fig. 14). 
Their appearance is exactly that figured by Saito (26; Pl. iti, 
Fig. 11g) for the sclerotium of A. nidulans. The asci were not 
developed, even in one culture which was kept for about five months 
after the sclerotia first began to form. 
The naked-eye colour of the vegetation is at first greenish- 
yellow, later a deep bright green, which does not become brownish 
and dull as in the case with Aspergillus glaucus. 
The upper (brown) portion of the conidiophore-stalk, and the 
conidia, survive heating in sulphuric acid; the sterigmata seem able 
to resist this acid when cold, but disappear on heating. The upper 
Fig. 14.—Aspergillus nidulans. Thick-walled cell from sclerotium. x 1,400. 
part of the stalk-apex is more fragile than the rest of the conidiv- 
phore, and is of a lighter brown colour; it is very apt to break away 
when the stalk is heated in sulphuric acid. Hydrochloric acid does 
not seem to affect any parts. Heating in caustic potash solution 
extracts a yellow colouring-matter from the mature green conidia. 
The conidia are apparently killed by exposure to temperatures 
of 26°—42° C., or even 38° C.; for cultures under these conditions 
not only did not germinate, but seemed incapable of doing so when 
transferred to room temperature. Under outdoor conditions ger- 
mination took place, but was delayed. The fungus did well at room 
temperature. (In the matter of their behaviour at higher tempera- 
tures, my specimens differ from A. nidulans as described by Lindau 
19, P- 139); he gives 38—42° C. as the optimum. He also gives 
8 » and 7 » as the lengths of the primary and secondary sterigmata 
t 
