MUSCULAR FIBRE-CELLS WITH THREE OR MORE FIBRES. 219 



becomes narrower, and at either extremity tapers into 

 a tendinous thread, which is inserted into, and is 

 indeed continuous with, the connective tissue. The 

 contractile matter itself appears perfectly smooth, and 

 under the highest powers exhibits a very faint stria- 

 tion in the longitudinal direction. In some of my 

 specimens a fibre has been preserved in a state of 

 contraction, when undulating swellings may be ob- 

 served at short intervals, giving to the fibre a beaded 

 appearance. (See the uppermost fibre in Fig. 1, plate 

 V, page 217.) If the bladder be examined at different 

 ages, the mode of growth of the muscular fibre cells 

 in length and breadth will be understood, and in the 

 bladder that has grown old it will be found that many 

 of the cells have degenerated into connective tissue. 

 In the adult bladder even, young muscular fibre cells 

 may be found, and the conversion of the contractile 

 material into fibrous tissue demonstrated. 



263. Muscular fibre-cells with three or more 

 fibres. The most remarkable muscular fibres are 

 those which have three, four, or even five tail-like 

 processes extending from the central triangular, 

 quadrangular, or pentangular mass of bioplasm. 

 These are found in considerable number in the thin- 

 nest parts of the bladder of the frog, hyla, and newt, 

 which correspond to the intercapillary spaces. 



From the uterus of the white mouse some beauti- 

 fully delicate spindle-shaped muscular fibre-cells may 

 be obtained. The muscular coat of the stomach and 

 small intestine of the same animal will also furnish 

 the observer with good specimens of muscular fibres. 

 In order to isolate these bodies, soaking in dilute 

 nitric acid, tearing with needles, and other chemical 

 and mechanical expedients have been recommended ; 

 but in the thin membrane which constitutes the frog's 

 bladder these cells are isolated ready for observation. 

 In the spaces between the vessels in specimens pre- 

 pared according to the plan I have recommended, 



