THE MUSCVLAR SYSTEM. 



279 



were continuous at cither cud with the perfectly normal 

 fibre.' 



1 [We are unable to agree altogether, either with the statement of the facts of the 

 development of muscle, or with the interpretation of them offered by Professor 

 Kolliker. In the first place, we 

 have been quite unable to discover 

 a sarcolemma in the foetal mus- 

 cular fibres, even at the seventh 

 month; on the other hand, the 

 edges of the discs formed quite 

 sharp projections (fig. 107 A, 1,4). 

 Even where, as in the case of 

 fig. 2, there was an appearance of a 

 sarcolemma, it could readily be 

 shown to arise merely from the 

 stretching of the transparent 

 matrix ; and that it did not pro- 

 ceed from any defined mem- 

 branous investment. 



According to Professor Kolliker, again, the sarcolemma is formed by the united 

 cell-membranes ; the proper muscular substance by the contents of the original cells. 

 At fig. 4 we have represented such " fusiform muscle-cells," from the triceps of a 

 seven-months' foetus, near its insertion into the tendon ; fig. 5 showing the transition 

 of the two tissues into one another. At a a, are the " nuclei," sometimes inclosed in 

 distinct cavities. Now we wish to draw particular attention to these points, viz. that 

 the " nuclei" of the muscle correspond exactly with those of connective tissue, and 

 therefore with the corpuscles of cartilage (see note, § 24) ; and, furthermore, that 

 the proper muscular substance and the sarcolemma are directly continuous with the 

 pseudo-fibrillated portion of the connective tissue, the one corresponding to its col- 

 lagenous, the other to its elastic clement. It necessarily follows then, (according to 

 what has been advanced in the note to § 24), that the muscular substance and the 

 sarcolemma are homologous with the matrix of cartilage; that, in short, as the 

 elastic and collagenous elements of connective tissue are the results of the chemical 

 and morphological differentiation of the matrix of the primitive embryonic tissue, — 

 so, the sarcous elements and the sarcolemma are the products of a corresponding 

 differentiation of the same primitive element. 



What that primitive matrix is, is a question, the consideration of which we must defer 

 as we have done before ; that it is not " cell-contents," however, is sufficiently obvious. 



The fibres of the foetus figured above, broke up into discs very readily while quite 

 fresh, and thus exhibited the peculiar dotting produced by the sarcous elements 

 (tig. 3). Many of the fibres appeared to have the edges of the discs double, as in 

 fig. 1. After a day or two (the weather being cold), the disposition to cleave trans- 



Fig. 107 A. 1,2, muscular fibres from a seven-months' foetus ; 3, discs, viewed 

 in section; 4, so-called muscle-cells, from the triceps of the same foetus; 5, junction 

 of the triceps with its tendon : a, " nuclei ;" b, bundles of connective tissue. 



