of Cecidomyide Larva, 163 
brane. Sometimes several of these balls are scen united in a 
common group. They haveat first a granular texture, but pretty 
quickly develope a number of cells, and finally, whilst the exter- 
nal form becomes gradually extended and the size constantly in- 
creases, are filled with a granular vitelline mass, which undergoes 
a segmentation, and then produces the embryo in its iterior. 
The latter, surrounded by a stratum of peripheral vitelline sub- 
stance, remains in its envelope until it has arrived at its full 
development. 
Meinert also adopts the notion of the production of the germs 
from the fatty body, and remarks, in its justification, that the 
latter, as the residue of the original formative material, might 
just as well be employed for the generation of a new brood as 
for the further development of the insect. 
As, however, Meinert, to all appearance, has not specially ex- 
amined into this question (his investigations were particularly 
directed to the later stages ef the development of the larva), we 
cannot lay any great stress on his acquiescence, especially as 
Pagenstecher in the course of his description repeatedly states 
expressly that the young germs (“ Her,” Pag.) possessed no true 
resemblance to the balls of the fatty body, and were never con- 
nected therewith. Pagenstecher therefore believes in the exis- 
tence of a proper germ-stock, although he songht in vain for any 
such structure, and found himself confined to mere suppositions 
with regard to the origin of the germs. He especially notices 
the possibility that these may have separated from the subcu- 
ticular cellular layer (the “hypoderma” of Weismann), and calls 
attention to the great development presented by these cells in 
the last segments of the body of our larve. The rectum also, 
below the opening of the Malpighian vessels, is surrounded by a 
group of cells which may perhaps likewise function as the place 
of origin of the germs. Certainly, he adds, “ the whole matter 
requires a further controlling examination.” 
As has been said, I have, in conjunction with Mecznikoff, 
turned my particular attention to this point, and I rejoice to be 
able to furnish the proof that the Cecidomyide larve really, as 
Pagenstecher supposed, possess a germ-stock. 
When the larvee just escaped from the skin of their parent’s 
body are examined underthe microscope with a moderate pressure, 
we see, in the posterior half of the tenth (or, including the head, 
the eleventh) segment, two clear roundish balls, which are situ- 
ated at the back, between the cords of the fatty body, here 
rather widely separated, and possess a diameter of 0:034-0-04 
millim. (PI.I.fig.1). These are the more easily discovered, because 
they lie almost immediately beneath the outer integument, and, 
during the contractions of the muscular apparatus, are moved up 
k 
