OBSERVATIONS ON STRIPED AND UNSTRIPED MUSCLE. 97 



Gerlach, Ketzius, and Bremer, should they prove to be correct, are 

 of importance. I think there is little doubt that the longitudinal 

 strise described by Gerlach are identical with the longitudinal bars 

 of the network figured by Retzius, Bremer, Melland, and myself. 

 Gerlach traced these stria? into connection with the nerve-endings. 

 Retzius showed the connection between the muscle-corpuscle and the 

 transverse strias, and Bremer traced the axis cylinder of the nerve 

 into direct continuity with the muscle-corpuscles. It therefore 

 appears that the network is connected with the nerve, and that the 

 longitudinal bars are connected with it indirectly through the trans- 

 verse networks. The direct continuity of the network with the 

 nerve does not necessarily imply that the network is itself nervous ; 

 in fact, it really supports the view that it is the part actively con- 

 cerned in contraction ; for we should expect, a priori, that if a 

 differentiation occurred in muscle, it would be with the contractile 

 part that the nerve would be in continuity. 



On the other hand, with regard to the transverse networks, it is 

 possible that they may be in part nervous in nature, and have for 

 their function the more rapid conveyance of the stimulus through 

 the muscle; and that the more rapid response to stimulus, the 

 special characteristic of striped muscle, may be partly explained in 

 this way. 



There are two obvious objections to the theory of contraction we 

 have arrived at, which I shall proceed to discuss : — 



1. It necessitates a difference between the longitudinal and 

 transverse bars of the same network. This is an objection, the real 

 nature of which it is impossible to determine in the present state 

 of our knowledge of the nature and import of intracellular networks 

 in general. In unstriped muscle the longitudinal fibrils are alone 

 present, and in the development of striped muscle the longitudinal 

 elements of the network appear first. The transverse networks 

 are described and figured by Betzius as direct processes of the 

 muscle-corpuscles ; the mode of their development is as yet un- 

 known, but should they prove on further investigation to develop as 

 processes of the corpuscles, it would follow that the two elements of 

 the network are, in spite of their close connection in the adult, of 

 entirely independent and different origin. And then a difference 

 of function would become not only possible but highly probable. 



