Notes on Some South African EntomojjJithoraceae. 
79 
" Specimen 3, 6.55 p.m. — This individual was sluggish and easily 
captured, but could still fly. 
" 7.10 p.m. — Can no longer fly, but can walk freely. 
" 7.20 p.m. — Can cling tenaciously, but when turned on its back cannot 
right itself. 
" 7.55 p.m. — Dead. 
10.30 p.m. — Conidiophores prominent. 
" No conidia given off yet." 
Individuals which were still quite active, but which had distended, 
white abdomens, were found on dissection to have the abdomen filled with 
spherical, hyphal bodies of regular shape and size, measuring about 40 /x in 
diameter. Just as the host is on the point of death these hyphal bodies 
germinate and grow with extraordinary rapidity, giving rise to the conidio- 
phores and in three to four hours producing conidia. 
Although the house-fly fungus has been much studied in different parts 
of the world, the occurrence of resting spores has only been recorded once. 
Winter (3) states that they are spherical, colourless, and 30-50 /xin diameter. 
No resting spores were found by the present writer, although some dozens 
of specimens were examined and several attempts were made to induce the 
formation of these spores by placing infected flies in conditions unfavourable 
to the fungus. It was found quite easy to inhibit the formation of conidia 
by placing specimens, immediately after death, in tightly-corked glass tubes 
containing a little calcium chloride. Exposure of only an hour to this dry 
atmosphere served to arrest the development of the fungus inside the body 
of the host. No conidia were formed when several infected flies were 
placed together in a small tightly-corked tube, and submersion in watei 
also served to prevent conidia formation. It was found that when once the 
development of the fungus had been checked in any of the above ways it 
failed to develop further, even when placed under the most favourable con- 
ditions. In the moist chamber the hyphal bodies broke down in the course 
of a few days, and in no cases were any signs of conjugation or the formation 
of resting spores seen. 
Both sexes of the house-fly seem to be attacked impartially, and vigorous 
individuals seem just as liable to infection as those that are spent. Several 
dead females were found whose abdomens contained large numbers of eggs. 
In 1912 Hesse (4) claimed to have succeeded in artificially cultivating 
E. muscacy and Bernstein (5) confirmed his results in 1914. No further 
work on this subject seems to have been done since the latter date. Hesse 
used as his culture medium the yolk of egg spread on glass slides and kept 
in a moist chamber. He states that he invariably obtained a profuse 
growth of the common mould Mucor racemosus from Empusa conidia sown 
on this medium. By feeding these Mucor spores back to adult house-flies 
he was able to produce epidemics of the disease at will. 
