The Comparative Phy.siology of tlie Pituitary Body 279 



and especially the colloid bodies, are furnished by the epithelial cells, but 

 it is possible that the ependyrna cells have also a secretory function. 



The pituitary body of elasniobranchs differs widely in structure 

 from that of the other classes considered. It is a gland which apparently 

 secretes directly into the blood-vessels, but it contains none of the deeply 

 staining (chromophil) cells which are characteristic of the anterior lobe of 

 mammals and teleosts. Its posterior lobe is absent or merely rudimentary. 



Extracts of the pituitary body of elasmobranchs have no immediate 

 physiological activity. 



The saccus vasculosus secretes its products into the ventricles of the 

 brain. Its extracts are inactive, and it is probably an auxiliary to the 

 choroid plexus, aiding in the production of the large amount of cerebro- 

 spinal fluid which is found in fishes. 



I have to thank Mr Richard Muir for the care with which he has 

 executed the accompanying illustrations. The expenses incurred have been 

 assisted by a grant from the Carnegie fund for research-work. 



LITERATURE REFERRED TO IN THE TEXT. 



(1) Gentes, " Recherches sur I'hypophyse et le sac vasculaire des vertebres," 

 Soc. scientif. d'Arcachon, Station biologique, Travaux des laboratoires, pp. 129-275, 

 fasc. i. Bordeaux, 1907. 



(2) Hallek, B., " Untersuchungeu iiber die Hypophyse und die Infundibular- 

 organe," Morpholog. Jahrhuch, Bd. xxv., S. 31, 1896. 



(3) Herring, "The Histological Appearances of the Mammalian Pituitary 

 Body," Quart. Journ. of Exper. Physiol, vol. i., No. 2, p. 121, 1908. 



(4) Howell, "Tlie Physiological Effects of Extracts of the Hypophysis Cerebri 

 and Infundibular Body," Amer. Journ. of Exper. Med., vol. iii., p. 245, 1898. 



(5) Magnus and Schafer, "The Action of Pituitary Extracts upon the 

 Kidney," Proc. Physiol. Soc, July 20, 1901. 



(6) Miclucho-Maclay, "Beitrag zur vergleichende Anutomie des Gehirns," 

 Jenaische Zeitschr. f. Naturwisscnscliaft, S. 557, 1868. 



(7) Oliver and Schafer, "On the Physiological Action of ILxtracts of the 

 Pituitary Body and certain other Glandular Organs," Journ. of Physiol., vol. xviii., 

 p. 277, 1895. 



(8) Osborne and Vincent, "A Contribution to the Study of the Pituitary 

 Body," Brit. Med. Journ., vol. i., p. 502, 1900. 



(9) Rabl-Ruckharu, "Das Grosshirn der Knoohenfisohe und seine Anhangs- 

 gebilde," Arch. f. Anat. u. Physiol., Anat. Abth., Jahrgang 1883, S. 317. 



(10) Schafer and Herring, "The Action of Pituitary Extracts upon the 

 Kidney," Phil. 'IVans., B., vol. cxcix., p. 1, 1906. 



(11) Sterzi, " Intorno alia struttura dell' ipotisi nei vertel)rati,'' Atti Accad. 

 Sc. Veneto-Trentino-Istriana, CI. sc. nat., fis. e. mat., vol. i., p. 72, 1904. Quoted 

 from Gentes. 



