528 
Royal Society Martin Barry’s 
there arise at this part two cells, which constitute the foundation 
of the new being. These two cells ’enlarge, and imbibe the fluid of 
those around them, which are at first pushed further out by the two 
central cells, and subsequently disappear by liquefaction. The 
contents of the germinal vesicle thus enter into the formation of 
two cells. The membrane of the germinal vesicle then disappears 
by li(]:uefaction. 
Each of the succeeding twin cells presents a nucleus, which, having 
first passed to the centre of its cell, resolves itself into cells in the 
manner above described. By this means the twin cells, in their 
turn, become filled with other cells. Only two of these in each 
twin cell being destined to continue, the others, as well as the 
membrane of each parent-cell, disappear by liquefaction, when four 
cells remain. These four produce eight, and so on, until the germ 
consists of a mulberry-like object, the cells of which do not admit 
of being counted. Nor does the mode of propagation continue the 
same with reference to number only. The process inherited from 
the germinal vesicle by its twin oflfspring, reappears in the progeny 
of these. Every cell, whatever its minuteness, if its interior can 
be discerned, is found filled with the foundations of new cells, into 
which its nucleus has been resolved. Together with a doubling of 
the number of the cells, there occurs also a diminution of their size. 
The cells are at first elliptical, and become globular. 
The above mode of augmentation, namely the origin of cells in 
cells, appears by no means to be limited to the period in question. 
Thus it is very common to meet with several varieties of epithelium- 
cells in the oviduct, including those which carry cilia, filled with 
cells ; but the whole embryo at a subsequent period is composed 
of cells filled with the foundations of other cells. 
In the second series of these researches, it was shown that the 
mulberry-like object above mentioned, is found to contain a cell 
larger than the rest, elliptical in form, and having in its centre a 
thick- walled hollow sphere, which is the nucleus of this cell. It 
was further shown that this nucleus is the rudimental embryo. From 
what has been just stated, it appears, that the same process, by 
which a nucleus in one instance transforms itself into the embryo, 
is in operation in another instance, where the product does not ex- 
tend beyond the interior of a minute and transitory cell. Making 
allowance, indeed, for a difference in form and size, the description 
given of the one might be applied to the other. It was shown in 
the second series, that in the production of the embryo out of a 
nucleus, layer after layer of cells come into view in the interior, 
while layers previously formed are pushed further out ; each of the 
layers being so distinctly circumscribed as to appear almost mem- 
branous at its surface. The same membranous appearance presents 
itself at the surface of the several layers of a nucleus in many situa- 
tions. Further, in the formation of the embryo, a pellucid centre 
is the point around which new layers of cells continually come into 
view ; a centre corresponding to that giving origin to similar ap- 
pearances in every nucleus described in the present memoir. It was 
