82 MUSCLE. 



the glands has an unknown special office beyond the function of 

 maintaining a constant supply of red and white 'blood-corpuscles, 

 and of caring for them when past usefulness. Such an opinion is 

 based upon the disturbance of the special glands in certain diseases, 

 and upon the great activity of these glands during foetal and infant 

 life, when the elaboration of the blood is necessarily very rapid to 

 maintain rapid development. In function, as well as in structure, 

 these glands are similar to lymph-glands. 



Has the spleen a special function ? 



The spleen becomes considerably increased in size during diges- 

 tion of food, and the tissue of the organ becomes filled with 

 albuminous particles which gradually disappear, and hence it is 

 inferred that there are special functions which have to do with the 

 elaboration of the nitrogenous foods. Besides this, the spleen may 

 be regarded as a prominent source of origin of both red and color- 

 less blood-corpuscles, and as the organ in which many of the red 

 corpuscles undergo degeneration when their usefulness is impaired. 

 Furthermore, it is a very vascular organ, and is capable of very 

 great distension, and becomes, in a passive way, a sort of safety- 

 valve in relieving the portal system, more especially of the 

 stomach. 



Can any special function be attributed to any other of the vascu- 

 lar glands? 

 No. 



MUSCLE. 



What kinds of muscular tissue are found ? 



1, plain or unstriated muscle-fibres; 2, striated muscle-fibres. 



Describe the unstriped or plain muscles. 



They are found in the tissues in which the will has no control, 

 and are known as involuntary muscles. These muscles are made up 

 of bundles of elongated, spindle-shaped cells. Each cell has an 

 oblong nucleus and is flattened (Fig. 20). In length they are about 

 ^tfff to ~3i)U i nc h< a d about ffajf inch in width. The cells are 

 bound into bundles by an albuminous cement, and these again 

 into larger bundles by areolar tissue. 



What is the appearance of the striated muscle ? 



This form of muscle-tissue makes up the most of the bodily 

 tissue, for it is found in all of the voluntary muscles. All such 



