718 E. V. COWDKY 



found in the posterior lobe, has quite a different staining reaction from 

 the content^ of the acini of the pars tuberalis in the ex. 



There is a very marked increase in size of the hypophysis, particularly 

 of the pars intermedia following removal of the thyroid, as well as after 

 castration in young animals. 



Pars Nervosa. The pars nervosa consists chiefly of neuroglia fibers 

 with a few scattered neuroglia cells (Fig. 4). True nerve cells are 

 absent. Both blood vessels and nerve fibers are of rare occurrence. Dark 

 greenish yellow pigment is often found free in the interstices between the 

 fibers and in the scattered neuroglia cells, as well as in the ependymal 

 cells lining the ventricular cavity. The distribution of this pigment has 

 been studied in detail by Kohn(a). Quite frequently the cells of the pars 

 intermedia tend to migrate into the adjacent portions of the posterior lobe. 

 Globules of colloid occur in the meshwork of neuroglia fibers, which are 

 formed in the pars intermedia, and are perhaps being discharged into the 

 third ventricle, as Herring believes. There is no anatomical evidence of a 

 secretion being formed by the posterior lobe itself, or of the presence in 

 it of "at least two specific autacoids," as claimed by Schafer on physio- 

 logical grounds. 



Gushing and Goetsch(a) daim to have show r n that the active principle 

 of the posterior lobe is discharged into the cerebrospinal fluid. This, how- 

 ever, is contradicted by Carlson and Martin, whose criticisms appear to 

 be well taken. Until the matter is finally settled, however, the possibility 

 should be always entertained that the material passes in both directions, 

 into the blood vessels and into the ventricular fluid, and, furthermore, 

 there is no reason to doubt that other physiologically active substances 

 which have escaped notice are liberated. 





