PITUITAKY BODY AND PINEAL GLAND. 425 



sional branches from the superior diaphragmatic or the pericardial. They 

 pass between the lobules, surround and penetrate the vesicles and form a 

 capillary plexus in their interior. The vesicles in this respect bear a certain 

 resemblance to the closed follicles of the intestine. The veins are also abun- 

 dant but they do not follow the course of the arteries. The principal vein 

 emerges at about the centre of the gland posteriorly and empties into the left 

 brachio-cephalic. Other small veins empty into the internal mammary, the 

 superior diaphragmatic and the pericardial. A few nervous filaments from the 

 sympathetic surround the principal thymic artery and penetrate the gland. 

 Their ultimate distribution is uncertain. The lymphatics are very abundant. 



As regards its chemical constitution, it may be stated in general terms 

 that the thymus contains matters of about the same character as those found 

 in the other ductless glands. 



Inasmuch as the thymus is peculiar to early life, one of the most impor- 

 tant points in its anatomical history relates to its mode of development. 

 This, however, does not present any great physiological interest and is fully 

 treated of in works upon anatomy. 



PITUITARY BODY AND PINEAL GLAND. 



These little bodies, situated at the base of the brain, are quite vascular, 

 contain closed vesicles and but few nervous elements, and are sometimes 

 classed with the ductless glands. Physiologists have no definite idea of their 

 uses. 



The pituitary body is of an ovoid form, a reddish-gray color, weighs five 

 to ten grains (O324 to O648 grammes), and is situated on the sella Turcica of 

 the sphenoid bone. It is said to be larger in the foetus than in the adult, and 

 in fcetal life it has a cavity communicating with the third ventricle. This . 

 little body has been studied by Grandry, in connection with the suprarenal 

 capsules. He regarded it as essentially composed of closed vesicles, with 

 fibres of connective tissue and blood-vessels. The vesicles are formed of a 

 transparent membrane, containing irregularly polygonal, nucleated cells and 

 free nuclei. The nuclei are distinct, with a well marked nucleolus. Capillary 

 vessels surround these vesicles without penetrating them. Grandry did not 

 observe either nerve-cells or fibres between the vesicles. 



The pineal gland is situated just behind the posterior commissure of the 

 brain, between the nates, and is enclosed in the velum interpositum. It is of 

 a conical shape, one-third of an inch (8'5 mm.) in length and of nearly the 

 color of the pituitary body. It is connected with the base of the brain by 

 several delicate, commissural peduncles. It presents a small cavity at its base, 

 and frequently it contains in its substance little calcareous masses composed 

 of calcium phosphate, calcium carbonate, ammonio-magnesian phosphate 

 and a small quantity of organic matter. It is covered with a fibrous envelope 

 which sends processes into its interior. As the result of the researches of 

 Grandry, it has been found to present a cortical substance, analogous in its 

 structure to the pituitary body, and a central portion composed of the ordi- 

 nary nervous elements found in the gray matter of the brain. Its structure 



