Betts— A Bee-hive Fungus , Pericystis alvei , Gen . 6^. Afoz/. 797 
The green colour, in the mature cyst, extends as far as the third septum ; 
the fusing hyphae can therefore be easily distinguished from the hypha 
bearing the cyst, by the septum near their distal ends (PL LXXV, Figs. 7, 8). 
When several cysts form on one hypha, their processes often all fuse 
with the same neighbouring hypha (PI. LXXV, Fig. 5). It has not been 
ascertained that this is invariably the case, so that any deductions from it 
as to a possible differentiation of the hyphae would be premature. 
The cyst is indehiscent ; the spores are presumably set free by the 
breaking of the wall. 
Pericystis alvei is not very easy to cultivate. It will germinate readily 
on most media, and produce mycelium and chlamydospores ; but cysts, if 
formed at all, are usually empty. The only satisfactory medium was found 
to be honey-gelatine. 1 On this the fungus developed normally and cysts 
containing spores were produced. 
Cultures of the fungus have a distinctly alcoholic odour. Gelatine is 
liquefied, but slowly ; the process is often one of softening rather than of 
liquefaction. 
Some rough experiments were made to test the effect of different 
temperatures on the germination of the chlamydospores. The results 
indicate that : 
(1) The chlamydospores will not germinate at 26°-$ 8° C., but do so 
when transferred from this to i5°-i8° C., so are not killed. The 
cultures were kept at 26°- ^H° for 13-16 days. 
(2) They germinate at 15°-! 8° C. in 1-5 days. 
(3) They germinate under outdoor conditions (mild winter weather) in 
about 11 days. 
These facts are of interest in view of the probable life-history of this 
species. In the spring the bees clean out their combs, throwing the plugs 
of mouldy pollen out of the hive. Some of the spores will, however, be left 
in the hive, and will remain there during the summer. When the stock 
swarms, the bees of the swarm probably take with them some spores 
adhering to their bodies, and so transfer the fungus to the new colony. If 
this be so, we can see that the inability to germinate at high temperatures 
is of use to this species. The temperature of the bee-hive when the bees 
are active is 32°-34° C. ; were the spores to germinate under these circum- 
stances, the bees would remove the fungus from the combs as fast as it grew. 
In the winter, on the other hand, the temperature does not usually exceed 
1 2° C. ; 2 and the fungus is able to establish itself unmolested by the bees, 
which are hibernating in a cluster in the central part of the hive. 
1 Diluted honey (three or four parts of water to one of honey), ioo c.c. ; gelatine (Gold Label), 
10 grm. The medium was usually left acid. 
2 The consensus of opinion seems to point to this as the temperature of the cluster when 
quiescent. The outer combs, where the fungus usually grows, are of course colder. 
