66 THE HOUSE FLY—DISEASE CARRIER 
They contain usually a large oil globule and are sur¬ 
rounded after discharge by a mass of protoplasm. 
If the conidium when discharged has come in con¬ 
tact with a suitable host insect, it adheres to it and sends 
out a hypha of germination which enters its body as 
just described. Secondary conidia are formed as a 
provision for further dissemination in case the primary 
spore has fallen on a substance unsuited to its proper 
development. With Empusa muscco the secondary con¬ 
idia are like the primary, or more commonly they are 
sub-ovoid, small, round at the apex, and formed by 
direct budding from the primary form. These also are 
discharged, but are apparently better suited to resist 
unfavorable conditions than the primary ones, and 
probably retain their power of germination much 
longer. 
There is also another morphological character of 
these fungi—the formation of simple hyphae which pro¬ 
ject out beyond the conidiophores. When they reach 
in the direction of the material upon which the de¬ 
stroyed insect stands they attach the body to it, and 
are then called rhizoids. W'hen they stick out in any 
other direction, however, they seem to be functionless 
and are called cystidia or paraphyses. The hyphae of 
attachment or rhizoids may be simple or variously 
branched, and their germination may be variously 
modified into an extended sucker. They do not seem 
to enter into soft substances, and their adhesion is ap¬ 
parently due to the presence of a viscous secretion. 
They are produced with great rapidity, appearing often 
