THE MUSCULAR TISSUE. 



1111 



plasm. In an amoeboid cell there is a framework of spongioplasm, which stains 

 with htematoxylin and similar reagents, enclosing in its meshes a clear substance, 

 hyaloplasm, which will not stain with these reagents. Under stimulation the 

 hyaloplasm passes into the pores of the spongioplasm ; without stimulation it tends 

 to pass out as in the formation of pseudopodia. In muscle there is the same thing : 

 viz., a framework of spongioplasm staining with hgematoxylin the substance 

 of the sarcous element and this encloses a clear hyaloplasm, the clear substance 

 of the sarcoinere, which resists staining with this reagent. During contraction 

 of the muscle i. e., stimulation this clear substance passes into the pores of 

 the spongioplasm ; while during extension of the muscle i. e., when there is no 

 stimulation it tends to pass out of the spongioplasm. 



In this way the contraction is brought about : under stimulation the proto- 

 plasmic material (the clear substance of the sarcoinere) recedes into the sarcous 

 element, causing the sarcomere to widen out and shorten. The contraction of 

 the muscle is merely the sum total of this widening out and shortening of these 

 bodies. 



The capillaries of striped muscle are very abundant, and form a sort of rect- 

 angular network, the branches of which run longitudinally in the endomysium 



FIG. 643. Non-striated muscular fibre. (From Kirke's Physiology.) 



between the muscular fibres, and are joined at short intervals by transverse 

 anastomosing branches. The larger vascular channels, arteries and veins, are 

 found only in the perimysium, between the muscular fasciculi. 



Nerves are profusely distributed to striped muscle. The mode of their 

 termination will be described on a subsequent page. 



The existence of lymphatic vessels in striped muscle has not been ascertained, 

 though they have been found in tendons and in the sheath of the muscle. 



The unstriped plain, or involuntary muscle, is found in the. Avails of the hollow 

 viscera viz., the lower half of the oesophagus and the whole of the remainder 

 of the gastro-intestinal tube ; in the trachea and bronchi, and the alveoli and 

 infundibula of the lungs ; in the gall-bladder and ductus communis choledochus ; 

 in the large ducts of the salivary and pancreatic glands ; in the pelvis and calices 

 of the kidney, the ureter, bladder, and urethra ; in the female sexual organs 

 viz., the ovary, the Fallopian tubes, the uterus (enormously developed in preg- 

 nancy), the vagina, the broad ligaments, and the erectile tissue of the clitoris; in the 

 male sexual organs viz., the dartos of the scrotum, the vas deferens and epididymis, 

 the vesiculae seminales, the prostate gland, and the corpora cavernosa and corpus 

 spongiosum ; in the ducts of certain glands, as in Wharton's duct ; in the capsule 



