132 MUSCLE. 
stance diminishes in quantity, the muscular fibres lie closer 
together, and have a more intensely white appearance upon 
the black ground. When some of this transparent substance, 
taken from a foetus of the size before mentioned (and in order 
to exclude as completely as possible the embryonal cellular 
tissue which surrounds the entire muscle, a portion should be 
cut out from the centre of the muscle), is examined with a 
magnifying power of 450, it exhibits various kinds of granules 
differing im size, and lying in a finely granulous mass. On 
examining these granules more accurately, they are found to 
vary, both in size and appearance, being round or oval, more 
or less opaque or transparent. A great many of them may be 
recognized as cell-nuclei by their form. In many instances, 
even when they are still connected together, the granulous 
substance around them is more or less distinctly seen to have 
a defined globular figure, within which the nucleus lies. This 
is, however, observed most distinctly when any of the granules 
become separated from the transparent substance, and float 
about in the fluid upon the object-glass. A quantity of globules 
are then seen floating about isolated, each one containing the 
characteristic cell-nucleus, which is placed eccentrical, varies 
much as to its size, and is often furnished with nucleoli. (See 
pl. III, fig. 13.) We are already familiar with this as the 
rudimentary form of most cells. The finely granulous_por- 
tion of the transparent mass is formed, in part, of the bodies of 
the cells, which, when in close contact, are difficult to distin- 
guish, and in part, of the cytoblastema in which the cells have 
been generated. Some of these cells which float about are 
becoming elongated into fibres, which are manifestly those of 
areolar tissue. Such instances, however, are rare, and these 
cells seem to be something quite peculiar. They might be re- 
garded as the primitive cells of new muscular fibres ; but from 
the manner in which Valentin expresses himself, one should 
infer that they are formed at a later period, for he says, 
“masses of globules begin to accumulate between the mus- 
cular fasciculi from the period at which they become trans- 
parent ;’ it is clear that he here refers to the nuclei of these 
cells. This must, therefore, remain an undecided point. 
We next examine the muscular fibres (primitive fasciculi) 
in the dorsal muscles of the same foetus. They do not all 
a Pres wy 
