DEVELOPMENT OF TRIOHOGRAMMA EVANESCENS. 181 
the egg grows rapidly the chorion becomes slightly stretched, 
and the lump of “ protoplasma spugnoso ” becomes pressed 
flat, and mechanically spreads around the egg (PL 10, fig. 4, 
X, X, X.). Now should the chorion by any chance burst, 
as it sometimes does, the extruded mass is released and lies 
near the egg and embryo (PL 11, fig. 27; PL 12, fig. 35, 
JSJXN.). 
In Pl. 10, fig. 4, the extruded mass ( EXN .) lies inside the 
chorion, and has been flattened out between the points X,X,X. x 
on the dorsal surface of the embryo, but on the ventral 
surface (F) the chorion, though somewhat stretched and 
thinner, is still recognisable, and cannot be confused with 
any other structure. The “ protoplasma spugnoso ” of 
Silvestri is an extruded dead mass, and is in no way com- 
parable or homologous with either the ammon or serosa of 
other insects, and since, as Silvestri shows, there is really a 
living embryonic membrane around the egg of Bncyrtus, it is 
incorrect, in my humble opinion, to say that “ LTnvolucro 
embrionale delL Oophthora e in parte omologo a quello delL 
Encyrtus.” In his figure on p. 67 of vol. iii, he depicts a 
membrane (P.) which has nuclei evenly distributed, and the 
tout ensemble is far more convincing than his fig. xxxvii, 6, 
of Oophthora. In the latter figure there are no nuclei in the 
“ pseudoserosa ” except those on one side, which he had 
already declared were “ in seguito degenereranno.” 
I feel convinced that in Trichogramma and Oophthora the 
“ pseudoserosa ” of Silvestri is merely an artefact produced 
by the mechanical flattening out of a waste mass of proto- 
plasm and chromatin. If the chorion bursts early no 
“ pseudoserosa ” can be formed. 
I agree with Silvestri’s description of the larva except that 
his fig. XL., p. 81, which, he says, is a sagittal section, he 
marks what I consider to be the longitudinal nerve-chord, 
as “ cellule muscolari M.” It is true that no properly 
differentiated muscles seem to exist in the larva of either 
species, and the movements of the animal are brought about 
by flattened mesoderm cells lying here and there under the 
