616 i General Notes. [Jure, 
egg, give rise to other cells. In fact, the central chromatin body 
of the primitive egg-cell, which he calls the 0d/ast, ejects a large 
number of chromatin pellets from its substance whic 
come the nuclei of the cells forming the egg-follicle. The conclu- 
sion at which Will arrives after reviewing the work of Fol, Roule, 
Sabatier, H. Ludwig, Balbiani and others, that in the ascidians, 
myriapods and insects, the nuclei of the follicular epithelium owe 
their origin to the primitive germinal nucleus or the ooblast, also 
holds good in respect to tha ova of birds and amphibians, is of 
great interest, and stands in sharp contrast to the old view that, 
the ovi-cell and epithelial ails of the follicle were both originally 
similar elements (germ-cells), but which have merely developed 
farther in widely differents ways. 
Will summarizes his results as follows: 1. The nuclei of the 
. oy ig epithelium are formed from the odblast. 2. The re- 
siduum of the ooblast becomes the germinative vesicle of the egg. 
3: Ove which are without a follicular epithelial investment, as is 
the case in numerous groups of animals, are homologous only 
with the egg plus the follicular epithelium of the higher forms. 
4. The egg of the Hemiptera is neither a cell nor an assemblage 
of cells, but the product of several cells. 5. The homological 
value of the eggs of different types is to be found in the fact that, 
in every case the ripe egg represents a germinal mass, in which 
are contained all the capabilities of future development, and which 
is the product of the activities of those cells which have shared in 
its construction. 
On THE DEVELOPMENT OF THE MAMMARY GLANDS OF CETA- 
cEA.—The following is an abstract of an account of some re- 
searches just completed for po aa gon this subject, founded 
upon nenii in the U.S. National Mus 
In ing longitudinal sections of the al A a female embryo 
of A B pa melas, two inches long, the microtome cut 
through the incipient mammary glands, one of which lies on 
r either side of the external genital opening. The 
direction of the plane of section is nearly ver- 
tical and transverse judging from the appear- 
ance of the consecutive series. The accom- 
‘ panying cut will give the reader some idea 
te of the appearance of these organs at the time 
they beats to be involuted or formed as thickenings of the epi- 
dermis of the young foetus of these huge mammalia 
The outer corneous layer of the epidermis or epiblast, eh, and 
al arse layer of the latter on the Malpighian stratum, ¢f’, are 
concerned in the formation of the first rudiments of the mam- 
> = 2m other mammalia. Although but a single stage was in- 
and not being aware of the existence of any previously 
researches upon this subject, it has been thought best 
