498 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



eral tendency upward and forward, both dendrites and neu- 

 raxons branching as they proceed onward, all traces of the 

 dendrites of the inferior and median cells of the lobe are lost 

 some little distance below the superior edge." After an allu- 

 sion to the vessels and fibrillated tissues that connect the in- 

 fundibulum with the posterior lobe, he says, "the whole ar- 

 rangement of the structures of the infundibulum" is "here 

 altered"; then, referring to both lobes, i.e., the hypophysis, 

 remarks, "elsewhere it shows no break in the described ar- 

 rangement, the line of differentiation between hypophysis and 

 infundibulum being sharply drawn, a layer of coarse connective- 

 tissue bundles being placed between and separating the gland- 

 ular and other structures of the pituitary from the tissues of 

 the infundibulum." It is clear that discontinuity of tissue is 

 a necessity in this location: a suggestive point in itself, since 

 Nature does not take such pains to isolate adjoining structures 

 without an object. 



Notwithstanding this striking autonomy of the organ, 

 there are several features in its histological make-up that may 

 enable us to detect the connecting-link between it and the in- 

 fundibular structures. Berkley refers to the "outer lamina 

 of slightly irregular ependymal cells (Fig. M, Plate I) three 

 or four deep, arranged after the manner of the cuticular epi- 

 thelium" This lamina, which older anatomists considered 

 as a continuation of the ventricular gray substance, only covers, 

 we have seen, the free portion of the posterior lobe and is not 

 continuous with the infundibular ependyma. Again, "there 

 are seen, extending from the thin capsule surrounding it" 

 (here Berkley alludes to the capsule that surrounds the entire 

 posterior lobe), "numbers of rather thick varicose threads, all 

 unbranched, and invariably ending, when their terminations 

 can be discovered, in a ball-shaped figure, at a definite line in 

 the substance of the body, usually at the inward ending of the 

 first layer of epithelial cells, at the line of separation from 

 the more centrally situated elements. These knobby threads," 

 he says, "strongly resemble the ependymal glia-cells of em- 

 bryonic life, and possibly may be related to them; but, as their 



10 All italics are our own. 



