434 
ME. E. A. SCHAFER ON THE MIN CTE STRUCTURE OF 
this means the oil becomes suspended in the gelatine in a state of extremely minute 
subdivision. If, after the mass has congealed, we make a thin section from the middle 
with a razor, and in the section so obtained examine the minute oil-globules with a 
high power, they are seen as dark dots each surrounded with a bright halo *. If we 
happen to come across several such little oil-globules, arranged in a row close to one 
another, we obtain the appearance of a line of dots in the centre of a bright band. 
The bearing of this simple experiment upon the production of the well-known cross 
strife of muscle is obvious. For in a muscular fibre there are regularly arranged rows 
of minute spheroids (the globular rod-heads), the optical effect of which may be con 
ceived to be quite similar to that of the minute oil-globules in our experiment, viz. to 
make the substance in which they are imbedded appear brighter in their immediate 
neighbourhood than it would otherwise be; by this means we obtain the appearance 
of the bright bands crossing the ground-substance, which have been described by all pre- 
vious observers, with the exception of IiEPPNEirf (with whom DonitzJ would seem 
to agree in this respect), as constituted by a distinct substance. 
It is further to be noted that the neck of each muscle-rod, the part where the head 
joins the shaft, is comparatively indistinct; this is due to the optical effect produced by 
the proximity of the globular head, and is contrary to what one would be led to expect 
if we assume this part of the rod to be imbedded in a clearer substance than the rest, 
for in such a case it would stand out the darker by the contrast. To this it is probably 
owing that previous observers have very generally failed in noticing the connexion of 
the row of dots with the rods. 
The appearance of a transverse section is corroborative of the view here taken of the 
production of the bright bands ; for in this case the dots are seen sufficiently close 
together for the optical effect produced upon the ground-substance by any one of them 
to be merged into that of the neighbouring ones, so that the intermediate substance 
appears uniformly bright. 
The close relation subsisting between the rows of rod-heads and their bright borders 
is also seen when a muscle contracts, the movements of the one proceeding pari passu 
with those of the other. 
A further indication that the whole of the ground-substance is of the same nature is 
to be found in the fact that, as will immediately be shown, it exhibits towards polarized 
light a similar behaviour throughout. 
In the state of rest this ground-substance pervades the whole muscular fibre ; in con- 
* This appearance occurs both when the globules are in focus and also when they are slightly out of the focus ; 
the surrounding brightness may be sometimes seen to be pretty sharply bounded by a margin, which is dimmer 
than the rest of the field. I am inclined to believe this to be an effect due to the interference between the 
rays of light which aro reflected from the surface of the globule and those which are refracted through its 
substance. Its bearing upon certain appearances sometimes observed in muscular fibres will bo noticed 
later on. 
t “ Ueber ein eigenthiimlichcs Yerhalten der quergestreiften Muskelfascr,” Schultze’s Archiv, Band v. (18G9). 
% “ Beitriige z. Kenntniss d. quergostr. Muskelf.," Reichert und Du Bois-Revhond’s Archiv, 1871. 
