The works of Francis Maitland Balfour, Volume 1 (of 4) : $b Separate memoirsBalfour, Francis M. (Francis Maitland)
Science
The works of Francis Maitland Balfour, Volume 1 (of 4) : $b Separate memoirs
Balfour, Francis M. (Francis Maitland)
Embryology; Zoology
Footnote 70: _Archiv für Micro. Anat._ Vol. XI. 1875.
Another interesting feature about the yolk is the presence in it of a
protoplasmic network. Dr Schultz has completely confirmed, and on some
points enlarged, my previous observations on this subject[71]. Dr Schultz's
confirmation is the more important, since he appears to be unacquainted
with my previous investigations. In my paper (_loc. cit._), after giving a
description of the network I make the following statement as to its
distribution.
"A specimen of this kind is represented in Plate 14, fig. 2,
_n.y_, where the meshes of the network are seen to be finer
immediately around the nuclei, and coarser in the intervals.
The specimen further shews, in the clearest manner, that
this network is not divided into areas, each representing a
cell and each containing a nucleus. I do not know to what
extent this network extends into the yolk. I have never yet
seen the limits of it, though it is very common to see the
coarsest yolk-granules lying in its meshes. Some of these
are shewn in Plate 14, fig. 2, _y.k._" [This edition, p.
65.]
Footnote 71: _Quart. Journ. Micro. Science_, Oct. 1874. [This
edition, No. V.]
Dr Schultz, by employing special methods of hardening and cutting sections
of the whole egg, has been able to shew that this network extends, in the
form of fine radial lines, from the centre to the circumference; and he
rightly states, that it exhibits no cell-like structures. I have detected
this network extending throughout the whole yolk in young eggs, but have
failed to see it with the distinctness which Dr Schultz attributes to it in
the ripe ovum. Since it is my intention to enter fully both into the
structure and meaning of this network in my account of a later stage, I say
no more about it here.
At one pole of the ripe ovum a slight examination demonstrates the presence
of a small circular spot, sharply distinguished from the remainder of the
yolk by its lighter colour. Around this spot is an area which is also of a
lighter colour than the yolk, and the outer border of which gradually
shades into the normal tint of the yolk. If a section be made through this
part (vide Pl. 6, fig. 1) the circular spot will be found to be the
germinal vesicle, and the area around it a disc of yolk containing smaller
spherules than the surrounding parts. The germinal vesicle possessed the
same structure in both the ripe eggs examined by me; and, in both, it was
situated quite on the external surface of the yolk.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account