

DISTRIBUTION OF ORGANIC MUSCLE. 199 



In the alimentary canal, smooth muscular fibres form mem- 

 branes, which are to be found from the lower part of the oeso- 

 phagus to the extremity of the large intestine. They also form 

 a proper layer in the mucous membrane, the so-called muscu- 

 laris mucosa, and in the small intestine extend from thence 

 into the villi. The excretory ducts of many glands possess a 

 proper muscular layer, as may be seen in the pancreatic duct of 

 the Ox, Cat, Pigeon, and Carp. 



According to Tobien, the ducts of all the salivary glands contain 

 muscular fibres ; but Kolliker only saw a few in Wharton's duct, and 

 Henle but a few in Steno's duct ; whilst, according to Eberth, they are 

 not present in the ducts of the salivary glands generally. 



Smooth muscular fibres are also found in the lymphatic 

 glands, and in the spleen. Opinions are, however, divided in 

 regard to the distribution of the muscular tissue in the latter. 

 In man, muscular fibres are contained in the capsule of the 

 spleen ; and some also maintain that they are present in the 

 trabeculse. The quantity of smooth muscular fibres in the cap- 

 sule of the spleen in various animals differs to a considerable 

 extent. They are very abundant in the porpoise, hedgehog, dog, 

 cat, pig, mole, rat, and rabbit, but exist only in small quantity 

 in the ruminants and in apes. In the pig, dog, ass, sheep, rab- 

 bit, horse, hedgehog, guinea-pig, peccary, bat, and cat, again, 

 nearly all the trabeculse contain muscular fibres ; but in some, 

 as the ox, these fibres are only present in the more delicate tra- 

 beculse. Smooth muscular fibres are also found in the walls of 

 the gall bladder, in the cystic duct, and in the ductus communis 

 choledochus. They constitute an essential portion of the 

 middle coat of the vessels ; they form connected laminae and 

 membranes in the parietes of the calyces and pelvis of the kid- 

 ney, and of the ureters and urinary bladder. They are found 

 beneath the mucous membrane of the prostatic and mem- 

 branous portions of the urethra, both in the male and female. 

 Smooth muscular fibres are widely distributed in the male sex- 

 ual apparatus, entering into the composition of the vas deferens, 

 the vesicula seminalis, the prostate, the corpora cavernosa, 

 Cowper's glands, and parepididymis ; between the tunica vagi- 

 nalis communis, and propria, and in the dartos. In the female 



