38 WILLIAM A. HASWELL. 
substance of the fibrils themselves. The appearances 
exhibited in fig. 5 will always present themselves when fibrils 
which have been sufficiently stained are isolated or nearly 
isolated—the line of the transverse network running through 
the substance of all the fibrils. Little pointed processes which 
project from the networks and lie between the fibrils become 
also visible in such preparations; these are distinguishable 
also in unstained bichromate of potash specimens. 
It is, however, by means of chloride of gold and formic acid 
that most. light is thrown on the nature of these transverse 
networks. But in drawing inferences from preparations made 
with these re-agents it is very necessary to check the results 
by a comparison with others prepared by other means; the 
fibres prepared in this way become greatly swollen, their 
length becoming increased by about a fifth and their breadth 
in even a higher ratio; so that in examining such prepara- 
tions the possibility of erroneous deductions as to structure 
being drawn from alterations brought about by the acid must 
be kept steadily in view. 
On looking at the glycerine preparation of the muscle treated 
with chloride of gold and formic acid (fig. 3), and comparing it 
with a fresh specimen, the most striking change that will be 
noticed is in the lateral contour; the fibres are almost inva- 
riably greatly dilated between the networks, so that the latter 
have the appearance of constricting girdles binding the fibrils 
together. This swelling of the general substance of the fibrils 
must involve a considerable strain on the transverse networks, 
and the result, as we shall see, is apparently in some instances 
a rupture of some of the elements of the networks. In parts 
of the fibres which are not greatly altered the transverse net- 
work presents the appearance of a band of granular spindle-like 
or oval bodies lying between the fibres, their long axes parallel 
with that of the fibre (fig. 13). Each of these granular bodies 
is connected with its neighbours by a number of delicate, thread- 
like processes (fig. 10). When a preparation in which the trans- 
verse networks have become strongly stained is crushed in 
glycerine under blows on the cover-glass the fibres often break 
