CH. XXV.] THE PINEAL GLAND 345 



there not constriction but dilatation of the blood-vessels, which 

 persists for a very long time. Adrenaline, on the other hand, con- 

 stricts the kidney arterioles. This dilatation is accompanied with 

 pronounced diuresis. It can hardly be doubted that this is no mere 

 accident, but that there is some definite relationship between the 

 activity of the posterior lobe of the pituitary and the kidney 

 function. It also stimulates milk secretion (Ott, Schafer). Extracts 

 of the anterior lobe produce neither a rise of blood-pressure nor any 

 effect upon the kidney or mammary gland. 



The pituitary body is essential for life. Paulesco, and later 

 Harvey Gushing and Horsley, found that total removal of the organ 

 is fatal in a few days. The same result follows entire removal of 

 the anterior lobe. On the other hand, removal of the posterior lobe 

 produces no such effect. Partial removal of the anterior lobe 

 produces a condition known as hypopituitarism, in which adiposity 

 accompanied by (or secondary to) atrophy of the organs of genera- 

 tion are the most marked signs. If the operation is done before 

 adolescence, there is a persistence of sexual infantilism. The trans- 

 plantation of the organ from another animal, or injection of anterior 

 lobe extracts, prolongs the life of animals after total extirpation, 

 or relieves the symptoms after partial extirpation. In many of 

 Horsley's experiments no such symptoms occurred, even although 

 only minute portions of the anterior lobe were left behind. 



The Pineal Gland. 



This gland, which is a small reddish body, is placed beneath the 

 corpus callosum, and rests upon the corpora quadrigemina. It is 

 composed of tubes and saccules lined and sometimes filled with 

 epithelial cells, and containing deposits of earthy salts (brain sand). 

 A few small atrophied nerve-cells without axons are also seen. 



In certain lizards, such as Hatteria, and in certain fishes such as 

 the lamprey, the pineal outgrowth is better developed and may be 

 paired. One division corresponds to the pineal gland; the other 

 becomes developed into an eye-like structure connected by nerve- 

 fibres to the habenular ganglion ; this third eye is situated centrally 

 on the upper surface of the head, but is covered by skin. 



The Coccygeal and Carotid Glands. 



These are situated, the one in front of the tip of the coccyx 

 and the other at the point of bifurcation of the common carotid 

 artery. They are made up of a plexus of small arteries, and 

 are enclosed and supported by fibrous tissue. They contain also 

 polyhedral cells collected into spheroidal clumps (carotid gland) or 

 irregular nodules (coccygeal gland). Some of the cells of the 

 carotid gland stain brown with chromic acid like those of the 

 suprarenal medulla. 



