DEVELOPMENT OP TRICHOGRAMMA EVANESOENS. 179 
•other papers more accessible to me. Since then I have 
been enabled, through Mr. Goodrich's kindness, to read 
Silvestri’s valuable articles. I have been impressed by the 
similarity between all stages in the development of Oophthora 
and of Trichogramma. To my eye, untrained in the apprecia- 
tion of small systematic differences in Chalcids, the adult 
insects in these species are closely similar, and the peculiar 
larvae of both species are structurally identical. 
Apart from differences due to different interpretation there 
is no doubt that the course of organogeny in these parasites 
is parallel. 
Silvestri (‘ Bolletino del Laboratorio de Zoologia Generale 
•e Agraria/ vol. i and iii) identifies the darkly staining masses 
of the inner region of the blastoderm stage (PI. 11, figs. 12 
and 13 in my drawings) as a “ piccolo numero di nuclei, die 
in seguito degenereranno,” but lias overlooked the small 
granule ( G-RC .) (if really present in Oophthora) which is so 
characteristic of stages such as that of PI. 11, figs. 12, 13, 
and 21. In Oophthora the germ cells have sunk into the egg 
before any marked differentiation of the primary germ 
layers has taken place (vide Silvestri, vol. iii, p. 78, fig. xxx, 
vii, 5), for it will be remembered that in the stage drawn in my 
fig. 15, PI. 11, the germ layers are distinctly forming and 
the germ cells still situated at the pole of the egg. 
Regarding Silvestri's statement that the extruded masses 
are nuclei, it might be well to mention that these darkly 
staining masses are but a part (i.e. the nucleolus) of the 
•original nuclei (see p. 11, and the figs. 13a and 21 of 
PI. 11). 
In Trichogramma I have not described the formation of an 
■embryonic membrane, nor do I believe that such exists. In 
Encyrtus apliidivorus and in Oophthora Slivestri des- 
cribes the formation of a “ pseudoserosa ” from a delamination 
of the surface cells of the embryo. He states : “ L'involucro 
embrionale dell* Oophthora h in parte omologo a quello dell’ 
Encyrtus, perche in questo sembra che derivi completamente 
per delaminazione delle cellule embrionali, mentre nell' 
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