Till I GERM- LA 



Ai .MM earl) period ai 'n the rain 



Mii>. -17, _'!'.' i, calh-d the infuiidihiiluiii 



fresao of the hypophysis and appli , .r wall of 



tin- latter, whi'-li it lias folded in fuaid the a i ' : opposite 



wall. 



Tl.i i by a M & ii-l. in which tin- >ac ami 



adjoining end of tin- infundilmlum are metamorphosed into tin- t\\o 

 Miplete organ already mei tioi .,1. 



The sac begins (in Man in half of the second 



Big) to 801 i <>ut from : | into the MM , 



connective tissue hollow tubn 



/<//'). Thes- are then detached from tin* walU of th. 



ly becoming enclosed on all >id-s l>y va>cnlar issue. 



In this respect the process of development agrees in the main with 

 thai of tin* thyroid inland, only that th.- .-plu-riral f Mirl.-s aiv li.-n- 

 represented by tubular structures. Aft -r ti sac has been 



\e,l into a large number of small, tortuous tub Med with 



narrow lumina, the lobe thus produc d aj>;>lis i; , tl,.- 



lower end of the infundibulum, with whii-li it 1 d by 



means of connective tis- 



The end of the infundibulum itself i- :ned in the 1- 



uto a small lobe of the In-nin. in \\hich, moreover, 

 ^.inglionic cells and nerve-fibres can be identified. In the higher 

 Vertebrates, on the contrary, no trace of such hlstological elements 

 can be detected in the posterior lobe of the hypophysis, which in 

 these forms consists of closely packed sji: m 1 thu 



a close resemblance to a spindle-cell sarcoma. 



(5) Development of the First or Fore-J> 



The most important change-, the comprehend >n of which is in 

 part attendel with serious difficult ii-s. take place in the vehicle of the 

 fore-brain ->i i-prehruni. It is divided (fig. 250), e . time of 



it> formation, as has air. ady hem n., _^ht and a left 



portion, owing to the fact that its wall becomes infolded from in 

 front and from above by means of a vertical pror.-.s of the connective 

 ti>sue envelope of the brain, the primitive falx. The two porti 

 the vesicles of the hemispheres (Am*), c.nn-> close together, being 

 M'pa rated by only the narrow longitudinal or interpallial ti^sui e ( iiisp), 

 which is iill. d up by the falx, so that their median StuH ome 



mutually flattened, whereas their lateral and under surfaces are 



