1894.] MICROSCOPICAL JOURT^AL. 145 



this kind of muscle works much more rapidly, than does 

 the unstriped muscle. From the fact that the striped 

 muscle is used in the skeletal muscles, most of which are 

 under the direct control of our will, it has often been 

 called " voluntary " muscle. In the g'ullet, however, it 

 is not at all under the control of the will and the act of 

 swallowing is only voluntary in its initial stages. This 

 kind of tissue is composed of "fibres" of great length 

 and very slender, the fibres are not cells, but are built 

 up out of cells. The exact way in which the cells are 

 arranged and the fibre formed is not sufiiciently under- 

 stood, but we may say that the nuclei of the component 

 cells are on the surface of the fibre where they are visi- 

 ble as elongate slender deeply staining masses, just below 

 a thin and very delicate membrane, the " scarcolemma " 

 which encloses the entire fibre. The nuclei of which 

 there may be a great many in one fibre are enveloped by 

 a network of protoplasmic fibres which reach out through 

 the fibre in every direction. The mass of the fibre is 

 composed of a chemical material called •' myosin " which 

 is physically very much like the white of an egg, that 

 is, it is semi-fluid and coagulates on boiling or on ex- 

 posure to acids. This substance of the fibre is placed in 

 the fibre in such a way that the fibre, when examined 

 microscopically, presents an appearance somewhat like 

 the surface of a ribbed ribbon. This appearance, thus 

 due to the way the myosin is arranged in the inside of 

 the fibre, has given the name of striped muscle to this 

 variety of muscular material. It seems to be probable 

 that the myosin is produced and arranged in the fibre by 

 the net work of protoplasm, if so then the fibre as we see 

 it is mainly the production of the real, but unseen pro- 

 toplasm. The views given in the cut on p. 143 show the 

 ordinary appearance of the fibre in both longitudinal (4) 

 and cross section (5). 



The Stomach difl'ers from the gullet in respect to both 



