DEVELOPMENT OP THE OVARIES IN THE BLOWFLY. 423 
Such an outstreaming of nuclear particles (JB alien) is un- 
doubtedly seen in the lowest nucleus of the egg, but it also 
occurs in the nuclei of the so-called nutrient cells, and in all the 
nuclei of the various organs of the larva during their degeneration 
in the first stages of the pupa. It is one of the most charac- 
teristic phenomena of yelk-formation, whether in the egg or the 
pupa, whilst it is quite unlike anything which has been observed 
in relation to the well-known germinal vesicles of other animals. 
Lastly, Henking (9) has quite recently figured and described 
the ripe ovarian egg of the Blowfly with the nutrient cells 
outside the chorion, and his figure has fortunately enabled me 
to discover the error into which Brandt and his followers have 
fallen. The appearance represented by Henking is an excep- 
tional phenomenon which I have frequently observed. When 
the eggs approach maturity they enlarge so rapidly that the 
anterior pole of an egg is often pushed iuto a chamber above 
it containing a half-developed ovum, which then assumes the 
form of a cap over the anterior pole of the ripe egg. I 
have sections which exhibit this phenomenon in several stages. 
Whenever the young ovum in the chamber above the ripe egg 
is present in an un-deformed condition the cap on the ripe 
egg is absent, and whenever a cap is present there is no second 
chamber in the egg-follicle. So many of the egg-tubes exhibit 
transitional conditions in which the ripe egg impinges upon or 
slightly indents the half-formed egg in the chamber above it that, 
with good sections, I cannot believe anyone would have the 
slightest doubt as to the nature of the phenomenon. 
2. The Development of the Ovaries and Ova. 
The earliest stage of development in which I have as yet seen 
the ovaries of the Ply is in the four-day old pupa (PI. XXVIII. 
fig. 4). In this stage they are apparently slightly iu advance of the 
stage described by Weismann as that of the seven-day-old pupa. 
The discrepancy is probably due to the fact that I worked in 
summer, and Weismann’s observations were made in winter. The 
earlier stages of the pupa are well known to be greatly influenced 
by the external temperature. 
nachher im Eiplasma aullo sen. Spater verscliwindet dag Keimblascken von un- 
seren Blicken, bis wir endlicb am oberen Eipol den Furchungskern wieder- 
finden” ( l . c. p. 12). 
