DEVELOPMENT OF TRICHOG-RAMMA EVANESCENS. 169 
there is the single median ventral germ-cell pocket, beneath 
the proctodaeum. 
In PI. 12, fig. 30 ( CU .), a distinct cuticle could be seen. It 
dipped into the pockets from which the horn-like jaw-pro- 
cesses protruded, and the latter are probably cuticular in 
nature. The thickening ( TH .) is ectodermal. Cuticle (chitin) 
was found in the stomodaeum, but I am not quite sure 
of its presence in the proctodaeum. It is possible that the 
processes are used for scooping up the yolk of the host as the 
larva feeds, and they are probably much modified mandibles. 
When the larva has swallowed all the yolk, very often not 
the smallest particle can be found outside its gut, and exactly 
how the yolk at the posterior end of the host's egg is worked 
to its mouth is impossible to say ; but it is probably by means 
of movements of the body that the unswallowed parts are 
brought forward. 
The Fate op the Extruded Matter. 
In PL 11, fig. 15, the extruded mass still lies within the 
vitelline membrane of the egg. As the larva grows the 
membrane becomes stretched and the waste mass flattened; 
but, though it remains intact for a good time, it eventually 
bursts. The extruded mass then floats free in the yolk of 
the Donacia egg. In PI. 11, fig. 27, EM., it is shown to the 
right of the ventral side of the posterior pole of the embryo. 
In PI. 12, fig. 35, it is seen quite close to the embiyo at EM. 
Curiously enough these fragments seem to live a good 
while, and nuclear changes, such as those undergone in the 
blastoderm, take place in some cases. 1 The mass may becom 
spherical, as in PI. 12, fig. 32, and may resemble the egg 
itself. Eventually the mass either degenerates outside the 
1 One is tempted to entertain the view that this peculiarity may he in 
some way or other connected with a faculty that culminates in the 
establishment of polyembryony. Were the extruded mass to contain 
enough live nuclei it might partially follow the development of the 
embryo. 
