264 ' Herring 



these he designates as the " segment juxta-nerveux," consisting of a few 

 layers of cells which have little affinity for stains, and are applied to the 

 posterior lobe in the middle line only. The other segment is formed by 

 the anterior lobe proper, and consists of chromophil cells. Both Sterzi 

 and Gentes deny the tubular character of the anterior lobe assigned to it 

 by Haller. Gentes found a small cleft — the remains of the sac from 

 which the epithelium of the pituitary is developed— in a young duck. 



The " segment juxta-nerveux " of Gentes and the chromophobe cells of 

 Sterzi agree in most respects with the cells which are here described as 

 belonging to the pars intermedia, but in all the specimens I have examined 

 they have a more extensive disposition than is assigned to them by Gentes. 

 The cells of the anterior lobe may be designated chromophil, but they have 

 not the remarkable affinity for stains which is possessed by the larger cells 

 of the anterior lobe of the mammalian pituitary. They certainly do differ 

 from the cells of the pars intermedia in staining property, and occasionally 

 deeply staining granular cells are found among them. 



Histological evidence points to the anterior lobe of the fowl's pituitary 

 being, like the mammalian anterior lobe, a gland which secretes directly 

 into the blood-vessels. The posterior lobe has an incomplete covering of 

 cells which are comparable with the cells of the mammalian pars intermedia 

 and are chiefly aggregated around its neck, as in some types of mammals. 

 The nervous tissue of the posterior lobe, with its epithelial investment, may 

 be regarded as forming a distinct organ which has probably a similar 

 function to that exercised by the posterior lobe of the mammalian pituitary. 

 It also resembles the mammalian posterior lobe in the occurrence within its 

 nervous substance of colloid or hyaline bodies. The colloid is, however, 

 confined to the nervous tissue of the lobe, and I have not seen it in or 

 between the cells of the pars intermedia. No colloid is found in the 

 anterior lobe proper. 



Physiological Action of Extracts of the Lobes of the 

 Fowl's Pituitary. 



Anterior Lobe. 



Extracts of the anterior lobe of the pituitary body of the fowl, when 

 injected intravenously, have little effect upon the blood-pressure, kidney 

 volume, and urine secretion. There is no change in the force and frequency 

 of the heart-beats ; the blood-pressure may show a very slight rise, as in 

 fig. 2, but is not much altered. Sometimes the pressure falls slightly and 

 quickly recovers, but I have not seen a marked fall after injection of 

 extracts of the fowl's anterior lobe. The kidney volume increases a little, 

 but not more than it does after the injection of a similar amount of 

 Ringer's fluid alone. 



The secretion of urine shows no change. Fig. 1 is a typical tracing of 



