A COMPARATIVE STUDY OF STRIATED MUSCLE. 39 
across transversely along the line of the transverse network 
(fig. 11), and in such a case it becomes clearly visible that the 
whole of the latter is a close reticulum of delicate threads, of 
which the granular-looking oval or spindle-shaped bodies are 
only condensed parts; and it becomes clearly evident also that 
the trabecule of the network freely invade the substance of the 
fibrils. 
Besides rendering evident the nature of the transverse net- 
works, the chloride of gold also brings into view a series of 
longitudinal and oblique threads running between the fibrils ; 
these are the threads of the longitudinal networks (figs. 7—10, 
13, 14). These threads mostly join the oval or spindle-shaped 
bodies of the transverse networks ; often a thread runs straight 
from one transverse network to the next, and may be traced 
through several, the spindles with which it is connected appear- 
ing to form a chain (fig. 13). In many instances the threads 
by which these bodies are connected together transversely into 
a transverse network are not to be distinguished, and the 
transverse network presents the appearance of a transverse line 
of oval or spindle-like bodies with more or less strongly marked 
outlines (figs. 9 and 15). This appearance must, I think, when 
comparison is made with fresh specimens and specimens pre- 
pared by other methods, be put down to the swelling and rup- 
ture by means of the formic acid; if the action goes a little 
further the bodies of the transverse network become much 
enlarged, with very well-marked outlines, and the longitudinal 
threads may also become greatly swollen (fig. 16). 
Oval bodies not unlike those above described are formed in 
similarly treated muscular fibres of the Frog ; but in the latter 
case they have nothing to do with the transverse networks, but 
are simply the altered nuclei of the muscle-corpuscles.! 
1 Compare Thin, “On the Structure of Muscular Fibre,” ‘Quart. Journ, 
Mier. Sci.,’ xvi (1876); Leydig, ‘‘ Ueber Tastkorperchen und Muskelstruc- 
tur,” ‘Miiller’s Archiv’ (1856); Bottcher, “Zur normalen und pathologischen 
Histologie der Muskeln,” ‘ Virchow’s Archiv,’ xiii (1858); Macallum, ‘On 
the Nuclei of the Striated Muscle-Fibre in Necturus lateralis,” ‘ Quart. 
Journ. Micr. Sci.,’ vol. xxvii; Sezelkow, “ Zur Histologie der quergestreiften 
Muskeln,” ‘ Virchow’s Archiv,’ xix (1860), 
