Studies on the function of the pineal body.

The pineal body was for a long time looked upon as a functionless remnant and from a phylogenetical point of view was accepted as a rudiment of the third eye, which is, at the present time, only found in hatteria punctata. As far as is known an epiphysis is present in all ver tebrates with the exception of mixinoids and crocodilia. In man the pineal body is pear shaped, lies just beneath the splenium of the corpus callosum resting upon the corpora quadrigemina. The gland varies in size shape and pigmentations and does not stand in any proportional relation in the size of the brain or the size of the body. According to UENIURA1, the average weight of the human pineal body is 0.157g. and it measures 0.84Cm. in length, 0.63Cm. in breadth, and 0.42Cm. in thickness. In mammal its size shows considerable variability, although in general cone shaped. Embryologicaly the gland is derived from a separate and distinct evagination of the roof of the third ventricle. A great quantity of literature upon the histological studies of the pineal body is found, and there is quite an abundance of knowledge on the histological structure of the gland, viz. parenchym cell, neuroglia, con nective tissue and nerve fibers. And as far as the structure is concerned, 1) UEIURA.