

NON-STRIATED MUSCULAR FIBRE. 



201 



They generally present nodosities or enlargements at frequent intervals 

 (Fig. 64) ; the character of which will be presently apparent. These 

 fibres are, like those of the other muscles, arranged in a parallel 

 manner into bands or fasciculi; but these fasciculi are generally 

 interwoven into a network, without having any fixed points of attach- 

 ment. It is of this kind of structure, that the proper muscular coat of 

 the oesophagus, of the stomach and intestinal canal, and of the bladder, 

 is chiefly composed. It has been recently shown by Prof. Kolliker, 

 that contractile tissue exists, even in the adult state of the highest 

 animal, under its very simplest form ; that, namely, of cells, which are 

 usually more or less elongated. These are composed of a soft, light 

 yellow substance, which swells in water and acetic acid, becoming pale 

 in the latter, and which is nearly homogeneous, so that it is difficult to 

 distinguish the cell-wall clearly from the cell-contents; but they are 

 especially characterized by the possession of long staff-like nuclei (Fig. 



Fig. 64. 



Fig. 65. 



A. A muscular fibre of organic life 

 from the urinary bladder, magni- 

 fied 600 diameters. Two of the nu- 

 clei are seen. 



B. A muscular fibre of organic 

 life, from the stomach, magnified 



'600 diameters. The diameter of 

 this and of the preceding fibre, 

 midway between the nuclei, was 

 l-4750th of an inch. 



Fusiform contractile cells: A, 

 trabecula of spleen, with the 

 cells in situ; B, a single cell iso- 

 lated; c, a similar cell treated 

 with acetic acid ; a, a, cells ; b, b, 

 nuclei. 



65, 5, >), which are sometimes only rendered perceptible by acetic acid. 

 These cells are sometimes so little elongated, especially in the walls of 

 the blood-vessels, that they might be taken for epithelium-cells ; on the 

 other hand, they frequently pass into the form of the non-striated fibres 

 already described. They are very commonly fusiform (Fig. 65, B), and 

 are then arranged in the manner shown in Fig. 65, A. This form of 

 muscular structure is often found without any admixture of other tissue, 

 as in the smaller arteries, veins, and lymphatics. But it is most com- 

 monly intermixed with the various forms of the simple fibrous tissues ; 

 and in this state it is found in the circular coat of the larger arteries 

 and veins, in the erectile tissues generally, in the skin, and especially 

 the dartos, to which it gives a contractility that is manifested under 

 the influence of cold or of mental emotions, and thus produces that 

 general roughness and rigidity of the surface which is known f as cutis 

 anserina, whilst it throws the scrotum into wrinkles. 



338, From the study of the early development of Muscular Fibre, it 



