OBSEEVATIONS ON STRIPED AND UNSTEIPED MUSCLE. 75 



Observations on the Structure and Distribution 

 of Striped and Unstriped Muscle in the 

 Animal Kingdom, and a Theory of Muscular 

 Contraction. 



By 



C. F. Marshall, M.Sc, 



Piatt Physiological Scholar in the Owens College, Manchester. 



With Plate VI. 



Striped muscle has long been known to occur widely dis- 

 tributed in the animal kingdom, but the details of the 

 structure of the striped muscle-cell have been the subject 

 of much controversy. Various descriptions have been given, 

 widely differing from one another, and none of them afford- 

 ing a satisfactory basis of comparison with other cells. The 

 demonstration of an intracellular network in the muscle- 

 fibre by several recent observers appears to afford the most 

 rational clue to its structure, for it not only explains all the 

 appearances seen in the muscle- fibre, including those seen 

 with polarised light in the living fibre by Briicke, but it also 

 renders possible a comparison with other cells, and shows that a 

 muscle-fibre is to be regarded as of essentially the same struc- 

 ture as an ordinary cell, and must not be considered as an 

 enigmatical structure, the details of which do not correspond 

 to those of any other cell in the animal economy. 



It is necessary first to examine the descriptions of the several 

 observers who have described a network in the striped muscle- 

 fibre and to consider the interpretation that they have put 

 upon it. In the following account I have only referred to those 



