Tin. 427 



chapter, i bo b" earned out in a -pe,-ial DUUmBB m. 



heini>pheir- <>f tl..- cerebrum Mini cerebellum inelu-ivc of 

 vermiform pFOOeOB,- that i- to Bay , OD tin- tuo part.- ol' tin- 1 

 which are covered \\ith a gray cortex. That the functional cajaritv 

 of the cerebrum and cerebellum depend- up m the extent of tin- 

 cortex and tin- regularly !!- in it. is to bo 



concluded from a larp- nuinl:T ol' plieiionifna. In this \v,. 

 explained tin- very \trn>i\e inci-i-a-c >f Miiiact- which i> lrou^ht 

 ahmit in the e<-rel>rum and corchflluin hy means of somewhat 

 dilYeivnt prucosses of folding. In the eerel.i-uin / 

 ai-i^e iVoin the medullary layer of the heini>jhertvs (centrum semi- 

 ovale), which, running in //>"//<////// '/'o?w, produce the 



characteristic relief i.f tlu- suita ";). In the cerebellum the 



Kfiti.1 



Fig. 240. -Lateral view of the brain of a human embryo from the first half of the fifth month, 



v-itural size. 



stl, Frontal lobe ; tchei.l, parietal lobe ; hi, occipital lobe ; m-hl.l, tfiuiioral lobe ; Sy g, fissure of 

 SYLVIUS ; m, olfactory nerve ; L-k, coivbelluiu ; br, pons; mob, medulla oblongata. 



numerous ridges proceeding from the medullary nucleus are narrow, 

 arranged pamlld to one another, and provukd with smaller accessory 

 (secondary and tertiary) ridges, so that the cross section of the 

 cerebellum presents an arhorocent figure (arbor vitse). 



If, after these preliminary remark-, we take under consideration 

 the metamorphoses of the five veadfiO, we may distini;nMi on each, 

 ! IHALKOVICS has done in his nicim^raph >!' the development of 

 the brain, four regions : floor, roof, u/i-f f>i-<> /"(> r1 ]><n-ts. \Ve shall 

 begin our description with the fifth vehicle, because in it- 

 it approaches most closely to th" -pinal cord 



(1) Metamorphosis of the Fifth /> 



The ftfth IraiH-veaick exhibit- in ditVerent x at the 



beginning of development (in the Chick on the second and third 



