704 SUMMARY OF CURRENT RESEARCHES RELATING TO 



this respect the posterior lobe of the pituitary is an infundibular gland. 

 Whether this substance is modified by its passage through the nervous 

 substance or not is unsettled. Its distribution corresponds with the site 

 of the tissue, the extracts of which have active physiological results when 

 injected into the blood. 



The anterior lobe of the pituitary is extremely vascular and its 

 circulation sinusoidal. The posterior lobe is supplied for the most part 

 by a central artery which enters it at its postero-superior angle, and runs 

 forward, giving off branches ; the veins begin immediately below the 

 epithelial investment and run backwards in this situation, to emerge 

 near the entry of the artery. The veins of both lobes enter large blood 

 sinuses lying close to the sides of the pituitary body. 



Histological evidence is against the statement of Bela Haller that 

 the anterior lobe is a tubular gland which pours its secretion directly 

 into the subdural space. 



Spiral Muscle-fibres.* — Ivar Thulin describes in the hyoglossus 

 muscle of Bufo agua and in the chameleon's tongue-muscle the occur- 

 rence of fibres with spirally arranged muscle-columns. He has found 

 similar structures in frogs and in the human uvula. 



c. General. 



Action of Extracts of Saccus Vasculosus and Pituitary Body.f 

 P. T. Herring has experimented with extracts of the saccus vasculosus 

 and pituitary body in certain fishes. In Elasmobranchs, e.g. Raia 

 batis, the saccus vasculosus is large and paired, and its lobes open by a 

 common median passage into the infundibulum, and so into the third 

 ventricle of the brain. In Teleosts it is single and situated in the 

 middle line between the inferior lobes of the pituitary body. In both 

 skate and cod the saccus vasculosus consists of a complicated sac fined 

 by a single layer of columnar epithelium, which is separated from 

 numerous large and thin- walled blood-vessels by a thin basement mem- 

 brane. The wall is thrown into folds, especially in the cod. 



Extracts of the saccus vasculosus made by boiling it in Ringer's fluid 

 have no marked physiological action when injected into the blood- 

 vessels of a cat. The results are practically those of an injection of 

 Ringer's fluid. 



The pituitary body of the skate, and, according to Gentes, of Elas- 

 mobranchs generally, has no posterior lobe. Nor does it possess the 

 granular cells of the anterior lobe of higher Vertebrates. Yet it is a 

 large body with the features of an internally secreting gland, and an 

 injection of its extract produces a slight fall of blood pressure, a dilata- 

 tion of the kidney, and some increase in urine flow. In Teleosts the 

 pituitary body consists of an anterior lobe proper characterised by the 

 presence in it of deeply staining granular cells, an intermediate part of 

 smaller clear cells, and a nervous portion. The latter is surrounded and 

 invaded by cells of the pars intermedia. Extracts of this portion of the 

 pituitary body, pars nervosa and pars intermedia, produce in the cat 



* Anat. Anzeig., xxxiii. (1908) pp. 241-52 (13 figs.). 

 t Quart. Journ. Exp. Physiol., i. (1908) pp. 187-8. 



