254 * W. M. Baldwia 



proceed directly up to the internal surfaee of the sarcolemma with 

 which they fuse. To each one of these cone-shaped sarcolemma 

 processes a Single tendon fibril is attached. These fibrillae vary 

 among themselves in diameter, the average size is, however, about 

 that of a muscle fibril, which, on the contrary, are generally uni- 

 form in size. Were the muscle fibrillae in direct continuity with 

 the tendon fibrillae then each one of the former must be reduced 

 greatly in diameter before becoming continuous with a tendon fibril. 

 There is, however, no morphological evidence of such a reduction 

 in size. 



Unlike the tendon end of the sarcolemma in such muscles as 

 are of the bipenniform type, the sarcolemma of these cone-shaped 

 processes is not noticeably tbickened. On the contrary, it is re- 

 markable for its uniform thinness. Were it thickened, one might 

 look therein for morphological evidence of muscle fibrillae, reduced 

 in calibre, passing along its surfaee or through its substance in 

 Order to establish a conjunction with the Single tendon fibril. 



I have already stated that the tendon fibrillae vary in size. 

 Such variations are not always proportionate, however, to the varia- 

 tions in size of the sarcolemma processes to which they are attached 

 or to the number of muscle fibrillae therein coutained. Such might 

 be the case were a direct continuity of the two structures present. 

 The absence of a correlation in size among these several structures 

 might be adduced, therefore, as an additional fact arguing against 

 the continuity of the tendon fibrillae with the muscle fibrillae. 



In the figure 6 two cells are demonstrated among the tendon 

 fibrillae. Judging from their morphological appearances and their 

 relation to the tendon fibrillae, I have concluded that such cells 

 were fibroblasts. In some instances I have found the tendon fibrillae 

 traversing the cell protoplasm. In the figure the larger of the two 

 cells gives oif two delicate fibrillae each of which is attached to a 

 pointed extremity of the sarcolemma. These are, moreover, the 

 only fibrillae attached to these respective sarcolemma extremities. 

 Upon the other side of the fibroblast several similarly slender fibrils 

 stream off in the general direction of the other tendon fibrillae. I 

 have, naturally, interpreted such fibroblastic processes as developing 

 tendon fibrillae, and upon this Interpretation have found an ex- 

 planation for the disparity in size between the several fibrillae i. e. 

 the smaller tendon fibrillae represent younger fibrillae. Hence the 

 size of such fibrillae is in no direct wise associated with the size 



