104 GENERAL ANATOMY OF THE TISSUES. 



coat, and in the trabeculce, mixed with connective tissue and elastic 

 fibres. 



6. In the Urinary organs the smooth muscles are found in the 

 calices and pelves of the kidneys, form a complete muscular layer in 

 the ureters and urinary bladder, but are only sparingly to be found in 

 the urethra.* 



7. The Female sexual organs possess smooth muscles in the oviducts, 

 the uterus, where during pregnancy their elements become excessively 

 developed, and attain a length of J of a line, the vagina, the corpora 

 cavernosa, and in the broad ligaments of the uterus in different places. 



8. In the Male sexual organs they are found in the dartos, between 

 the t. vaginalis communis and propria, in the vas deferens, vesiculse 

 seminales, the prostate, around Cowper's glands, and in the corpora 

 cavernosa penis. 



9. In the Vascular system smooth muscles exist in the tunica media 

 of all, especially of the smaller arteries ; also in that of most veins, 

 and of the lymphatics, with the exception of the finest ; furthermore, 

 in the lymphatic glands (Heyfelder) ; and lastly in the tunica adventitia 

 of many veins. The elements, in vessels of middle dimensions, are 

 everywhere fusiform fibre-cells : in the large arteries, on the other 

 hand, shorter plates, which often resemble certain forms of pavement 

 epithelium ; and in the smallest arteries they are more elongated, or 

 even round cells, forms which must be considered as less developed. 



10. In the Eye, smooth muscles form the sphincter and dilator pu- 

 pillce and the tensor choroidece. 



11. In the Skin, lastly, this tissue appears besides in the dartos, 

 in the form of minute muscles upon the hair sacs, in the areola, and 

 in the nipple, and in many of the sudoriparous and sebaceous follicles. f 



The elements of the smooth muscles were formerly universally re- 

 garded as elongated bands containing many nuclei, which were sup- 

 posed to be developed by the coalescence of numerous mutually applied 

 cells. In 1847 I showed that this is not the case ; that, on the other 

 hand, the elements of these muscles are only modified simple cells ; and 

 at the same time I demonstrated, that these contractile fibre-cells occur 

 wherever contractile connective tissue had previously been assumed to 



* [Mr. Hancock (On the Anatomy and Physiology of the Male Urethra, London, 1852), 

 who had made out the existence of the organic muscular layer in the urethra indepen- 

 dently, attributes to it much more anatomical and physiological importance. (See below, 

 Urinary Organs.) TRS.] 



f [These muscles have also been seen by Mr. Lister (Quart. Journal of Microscop. 

 Science, vol. i. p. 203), in the scalp. Mr. Lister found the muscles in this situation smaller 

 (y^th of an inch) than those measured by Kolliker. They possessed extremely distinct 

 nuclei, but instead of uniting in flat bundles were often circular, sometimes elliptical or 

 polygonal. DaC/j 



