DR. MARTIN BARRY’S RESEARCHES IN EMBRYOLOGY. 
541 
35/. The outer cells of the germ are often more transparent in and near the centre 
than under their membrane (figs. 210. 216. bs). This seems referable to the presence, 
in and near the centre, of cells which are attaining their greatest size; while under 
their membrane there is a layer of dark objects. The latter seem to be the founda- 
tions of new cells, and probably formed the central part of the interior of larger cells, 
the membranes of which have disappeared by liquefaction. Subsequently these peri- 
pheral dark objects become situated between the advancing inner cells, and then we 
meet with such appearances as those in figs. 218. 221. We thus find that the pro- 
cess described as in operation within the germinal vesicle, and as producing the 
changes in appearance of the substance surrounding it (par. 351. and Plate XXiV. 
figs. 191. 193, Plate XXV. figs. 196. 199, Plate XXIV. figs. 188. 189. 179.), manifests 
itself even in the minutest cells which can be examined. States of the entire ovum 
are also met with, which, as viewed with a low magnifying power, very much resemble 
the condition of one of the minute cells in question, and undoubtedly from the same 
cause ; namely, that which has been now described. 
358. In each 'of the cells Plate XXVII. fig. 229. bs, an object remained at the pe- 
riphery; so that each cell with this object resembled the germinal vesicle with that 
particular state of the germinal spot in Plate XXII. fig. 156. The object in question in 
the cells fig. 229. corrresponded in its situation to that known as the nucleus of the cell, 
or “cytoblast” ; but its free part seemed on the point of being resolved into other cells, 
the central part presenting a finely granular appearance, and a point in the middle, 
which in some instances was pellucid, and in others dark. In the cells fig. 230. bs, 
such an object was situated, not at the periphery, but in the centre of each cell. The 
object here seen, however, corresponded only in appearance to the object In fig. 229 ; 
for that portion which in fig. 229. seemed about to become resolved into new cells, 
had in fig. 230. actually formed them, and they filled the parent cell ; while the inner 
portion, which in fig. 229. had a finely granular appearance, now presented in its 
turn the foundations of new ceils. 
The rudhnental Embryo is the Nucleus of a Cell. 
359. A vesicle discovered in my ‘‘Second Series” and described as containing 
“ the true gertn”'j~ (/. c., Plate VI. fig. 1 13.), is present in such states as those repre- 
sented in Plate XXVII. figs. 223. 224, but not easily seen. It is shown in outline in 
fig. 223, in or near the centre of a group of cells (bs) ; and in fig. 225. is delineated 
its apparent state, as seen in the group fig. 224. The nucleus, however, was the only 
part of this cell which could be distinctly seen. Other appearances of this object are 
represented in figs. 226 and 228. In subsequent conditions the cell has sometimes 
appeared quite dark (fig. 232.), apparently from globules in its fluid; in other in- 
stances it has been found much more transparent (fig. 233.). In fig. 228. the nucleus 
f In strictness, this term belongs rather to the objects to which I have applied it in the present memoir, 
namely, to the twin cells bs as well as to their successors bs, and therefore to the whole group, or entire mul- 
berry -like object, containing the vesicle above referred to, and including that vesicle itsd f 
