

HISTOLOGY OP THE POSTERIOR PITUITARY. 497 



They are small and round, and give off strong dendrites, which 

 appear knotted or covered with thorns, giving them a "prickly 

 appearance" (Fig. J, Plate I, and Fig. /, Plate III). Another 

 variety found in abundance in this region is a small cell with 

 a rich, apical tuft of fine, wavy processes. They are also dis- 

 tributed in the midst of a net-work of varicose nerve-fibers 

 (Fig. K, Plate I, and Fig. fc, Plate III) in the upper and near 

 the anterior border of the lobe "along the space formerly occu- 

 pied by the infundibular duct." As already stated, the spider- 

 cell is to be found in great abundance in this locality, which, 

 added to the other two varieties of cell, gives us three main 

 cellular elements as representatives of the class of cells found 

 mainly or only in the upper infundibular region of the organ. 



What is the nature of the organ's functions? That it is 

 not a secreting organ seems obvious; there is no evidence that 

 it contains ducts. May it produce an internal secretion? The 

 vascular channels, intrinsic and extrinsic, are smaller than 

 those of the anterior lobe, and the latter does not produce an 

 internal secretion. Such being the case, notwithstanding its 

 far greater vascular supply and a much less complex nervous 

 organization, it is not likely that its mate, the posterior lobe, 

 should be the seat of such a secretory function. Indeed, the 

 embryological development of the latter and its anatomical 

 relations disprove this completely, while they pointedly sug- 

 gest a marked kinship with the anterior lobe as to intrinsic 

 function: i.e., as a center for the conversion of chemical energy 

 into mechanical energy, a perfectly logical deduction when we 

 note the presence of the same closed glands, or alveoli, includ- 

 ing the colloid substance, and their close anatomical relation- 

 ship. Indeed, everything tends to suggest that, what the ante- 

 rior pituitary body is to the adrenals, the posterior pituitary 

 body is to the general nervous system. 



And, yet, what is the connecting structure between the 

 posterior pituitary body and the parts to which, under such 

 conditions, its energy would be supplied? There is no evi- 

 dence, according to Berkley, that any of the nervous elements 

 of the infundibular lobe itself pass beyond its limits into the 

 infundibulum. His histological work shows that, while "all 

 the axis-cylinder processes and the long dendrites have a gen- 



