306 STUDIES IN ADVANCED PHYSIOLOGY. 



relatively large size in early life would indicate that either 

 lymphatic tissue has not appeared abundantly in other parts 

 of the body, or that in the growing organism there is an 

 especially great demand for new cells. Unlike, however, 

 ordinary lymphatic glands, the thymus seems richly sup- 

 plied with blood-vessels. Fine vessels penetrate to the in- 

 dividual follicles, forming a plexus around them and send- 

 ing converging capillaries into the medullary portion. The 

 lymphatics which transverse the interstices of the gland are 

 very large. It is poorly supplied with nerves, although a 

 few filaments derived from the pneumogastric and the sym- 

 pathetic system reach the gland by way of its arteries. 



5. The Carotid Glands. Situated just above the point 

 at which the common carotid artery on each side divides 

 into an internal and external branch there is a small gland- 

 ular nodule called the carotid gland. It has a connective 

 tissue capsule, trabeculse from which extend into the in- 

 terior, dividing it into small lobules. These lobules are 

 composed of masses of epithelium-like cells, around and be- 

 tween which there are distributed numerous blood capillaries. 

 Their physiological importance may be dismissed by saying 

 that we have absolutely no knowledge as to what their func- 

 tion is. 



6. The Coccygeal Gland. The coccygeal gland is a 

 small glandular nodule only two or three millimeters in 

 diameter, situated at the apex of the coccyx. It does not 

 differ materially in structure from the carotid glands, being 

 composed of masses of epithelium-like cells surrounded with 

 blood capillaries. Concerning this gland we are also com- 

 pletely in the dark, both as to the manner in which it de- 

 velops and as to its function. 



7. The Pituitary Body. Situated at the end of the in- 

 fundibulum of the brain (which see) there is a small glandu- 

 lar nodule about the size of a small pea known as the 

 pituitary body. It is enclosed in a special prolongation of 

 the dura mater and is composed of two lobes. In color it 



