ga 
FLIES. 415 
name to Empusa, or rather Empusina, the first of these names be- 
ing already occupied. Hestates that the vesical filaments termin- 
ate in the abdomen in a continuous,often branched tube and consist 
therefore of a single tubular cell. The upper free end, however, be- 
comes cut off by a septum, and the terminal cell acquires a compan- 
ulate form and a dark color; when ripe it is thrown off with some 
force, and a number of these form the whitecloud above mentioned. 
You have all no doubt observed this halo or oriole. It always re- 
minds me of pictures of certain mediaeval saints in old books; after 
having led a more or less saintly life in some wilderness or cave, 
they died either of old age or self-inflicted starvation, or were 
pinned up like an insect by some heathen (not an entomologist); but 
the old masters never failed to paint them with this halo of light 
surrounding their reverend heads, thus indicating their belief that 
light never could penetrate any further in that particular direction. 
Mr. Cohn endeavored in vain to make them (spores not saints) 
germinate; and nothing like them were found in the cavity of the 
abdomen of numerous flies in which the filaments were traced in 
their earlier stages. Mr. Griffith inclines to regard them as peridi- 
oles or spore-cases; or they may be stylospores, which after a stage 
of rest produce an intermediate mycelial structure, and then give 
birth to the ripe spores. 
When we turn our attention to the poor sufferer,we observe no out- 
ward signs of the disease in its early stage; yet observing carefully 
great numbers of flies we soon detect some that differ from the rest by 
a moreerectabdomen and by theirawkward methodof walking. At 
first they are restless,constantly running and flying about. Ifthe dis- 
ease, however, grows worse,their motions become very sluggish and 
if you approach them with your finger they either do not fly away 
at all or in a very clumsy way, soon settling again. At last they are 
unable to walk more than a few steps. About an hour before they 
die,all intentional motion ceases,and the fly fixes its proboscis firmly 
to the object it happens to have settled upon, only the legs spas- 
modically contract and extendin a very unsymmetrical way. The 
abdomen gradually swells and shows on its underside a whitish 
color; the upper surface of the insect, however, does not change at 
all, and no trace is as yet visible of the white rings between the seg- 
ments, nor is any white dust to be seen. Gradually all motion 
ceases,and the animalis dead. Atter death the abdomen still swells, 
and about eight hours later it is so much extended that the segments 
are pulled apart, and the fine connecting skin between them becomes 
visible. And here a white substance gradually is pushed out from 
the interior, so that eventually three white and parallel rings or 
belts are formed. The first trace of loose dust becomes now visible 
under the insect. The fly remains unaltered in this condition for 
several days, only that these belts become more prominent and fre- 
quently a white ring is also visible between head and thorax. The 
dust around the dead fly becomes denser, the corpse eventually dries 
up, the white belts disappear, and the body shrinks, so that the fly 
appears as a living one, though wings and legs are covered with 
dust. Thus far all the symptoms could be followed with the naked 
