364 



e KuPFFER vogliauo ouiologizzare il primo all' epiphysis dei vertebrati 

 superiori, il secondo alia paraphysis; le ricerche numerose suUa diffi- 

 cile questione, egregiamente esposte da Gaupp ^) e da Studnicka ^j, 

 dimostrano insostenibili tali omologie, L' epiphysis infatti si produce 

 da un' estroflessione del pedunculo deH'organon pineale, la paraphysis 

 e un organo a struttura glanduläre e, come giä avvertii, non e cou- 

 frontabile ne per sviluppo, ne per sede, iie per struttura airorgauoti 

 parapineale. 



Studnicka ^) ha potuto dimostrare per mezzo di numerose ricerche 

 d' anatomia comparata che 1' organon pineale va scomparendo nei verte- 

 brati superiori mentre dalla sua parte prossimale si produce 1' epiphysis, 

 che acquista talora enorme sviluppo: 1' organon parapineale va pure 

 scomparendo e solo talvolta, come nei rettili, rimane ben manifesto e 

 costituisce allora 1' organon parietale. (Schluß folgt.) 



Nachdruck verboten. 



The Radix meseiicephalica trigemiiii. The Graiiglioii isthmi. 



By J. B. Johnston. 

 With 8 Figures. 



A fiber bundle the existence of which in the brain of man and 

 mammals has long been known is described as a root bundle of the 

 trigeminus which takes its origin from cells in the roof of the mes- 

 encephalon and is considered to be motor. The certainty with which 

 the tract in man is traced leaves nothing to be desired (1, p. 286 to 

 392), but that its fibers are motor in character is not so clear. This 

 interpretation seems to be due to the fact that the bundle usually 

 joins the motor root at its exit from the brain. P'urther study of 

 the exact relation of these fibers to the roots is needed. Miss 

 Sabin (22) states that they sometimes enter the sensory root. Other 

 facts regarding this bundle are also of great significance. The 

 origin of its fibers from the large cells of the mesencephalon which 

 are regarded as its nucleus, has not been demonstrated. These cells 

 do not have the appearance of motor cells in other parts of the brain 

 or cord and are exceedingly hard to impregnate by the Golgi silver 

 method. They lie in the roof of the brain while all other motor 

 nuclei lie in the floor. Similar large cells are found along the whole 



1) Op. cit. 



2) Op. cit. a p. 346. 



3) Op. cit. a p. 360. 



