I'lTl ITAHY (iLANI). 



1175 



A. 1'.. :iii(l .-it'tcr his time far into tin- luiddir a<i'e.s, oven 

 if the e()iice|iti(iii was uiodified in se\eral manners, tiie 

 cerebral hypophysis was explained as an extremely im- 

 portant organ for the purification of the fluids contained 

 in tlie lirain. It was also called the gland for the se- 

 cretion of the nasal mucus (r/huuhild 2)ifiiifaria). an error 

 which was not refuted until the seventeenth century. 

 Another opinion was advanced, whicii even at the be- 

 ginning of the present century was maintained by so 

 eminent an anatomist as Meckel, namely that it secreted 

 some kind of important fluid, which was supplied to 



A 



fa-tal life tiian afterwards and is comparatively larger in 

 young ]iersons than in old, as is the case with several 

 other organs wiiose significance ajipears to be more 

 historical than physiologically clear. 



Better than its function, however, we know the 

 origin of the iupophysis". In man it arises as an in- 

 volution of the cmbr\onic ectoderm in the region which 

 afterwards becomes tiie roof of the mouth cavity. Tiiis 

 involution rises, towards the anterior end of the noto- 

 chord. It makes its appearance before the mouth ca- 

 vity proper is formed, and long before the mouth has 



J'ubcOi 



2.1 Mdb 



Fig. 34lj. Longitudinal section of tlie forepart of Jarvie of Petromyzon Ptaneri, after A. Pohbn. A three days, B six (lays, U seventeen 



days after exclusion. 



<7(, cluirda dorsnlis; Eiit, entoderm: Ep. epiphysis; Hy, hypojiliysis; /»/, infundibulum ; M, stomodieuin, future mouth cavity; Max, upper 



jaw; MM, lower jaw; MT, mouth tentacle; N, nasal sinus, future nasal cavity; Thr/, thyreoid gland; Tub. cin, tuber cinereum. 



the third ventricle of the brain. In modern days phy- j broken a passage through the pharynx to join the in- 

 siology does not seem to devote very much attention to ! testinal canal. In the form of a tube it grows u]; to- 

 its interpretation: it is most generally referred to tlie ' wards the rudin)ent of the bi-ain; and when the floor 



so-called blood-vascular glands, which it resembles in 

 the greater part of its structure. Remarkable is the 



of the skull is developed the lower part of this tube 

 closes, in the region where the presphenoid bone sub- 



■ircumstance that it lias a more robust growth during ' sequently coalesces with the postsjihenoid: the comnui- 



" The first investigator hereof was Rathke, Ceber die EulMehnng der Glaiidula pitiiitavia, Miillers Arcliiv 18.38, p. 482. 



an,linari„n Fiskc 



