THE MUSCULAR TISSUES. 50 



4. The Male Generative Organs: in epididymis, vas deferens, 

 vesiculae seminales, prostate body, Cowper's glands, cavernous and 

 spongy bodies of penis. 



5. The Female Generative Organs: in oviducts, uterus, and 

 vagina ; in the erectile tissue of external genitals ; in broad and round 

 ligaments, and in erectile tissue of nipple. 



6. The Respiratory Tract: in the posterior part of trachea; 

 encircling bands in bronchial tubes, and bundles within pleura. 



7. The Vascular System. : in the coats of arteries, veins, and 

 larger lymphatics. 



8. The Lymphatic Glands : in the capsule and the trabeculae of 

 spleen ; sometimes in the trabeculse of lymphatic glands. 



9. The Eye : in iris and ciliary body, and in eyelids. 



10. The Integument: as the arrectores pili connected with the 

 hair-follicles ; in sweat and some sebaceous glands ; in skin covering 

 the scrotum and parts of the external genitals. 



Involuntary muscle is composed of delicate spindle, often rib- 

 bon-like, fibre-cells ; these vary 



greatly in size, measuring 75-225 FIG. 68. 



/** long and 4-8 /* wide. The 

 cells found in arteries are short 



FIG. 67. 



Isolated involuntary-muscle cells from intestine Involuntary-muscle cells from mesentery of 



of man. newt : n, nuclei ; f, axial fibre ; m, transverse 



markings on surface of cell ; B, muscle-cell with 

 forked extremity. 



and flat, being but 25-45 f- l n g an< 3 9-1 2 AI wide ; the largest ele- 

 ments are found in the gravid uterus, where they reach a length 



i M (micron.} = the loooth part of a millimetre. 



