819 



d. AhiI'Ins Kappers' Studies on the ontogeny of the corpus strialuni 



of birds. 



Ill a recent paper Ariëns Kappkhs (1922) reported tiie results of 

 Ills investigations upon the ontogenetic development of the different 

 parts of the striatum complex in liirds. He concludes that apait 

 from the archistriatum "at least two chief divisions of the striatum 

 may be distinguished: the palaeostriatuni, which is enlarged to a 

 p<ü(ieostriatuin aiupnentatniii (or meso-striatum) and which arises 

 entirely from the base of the brain in front of the recessus prae- 

 opticus, and the hyperstriatum of which the upper part arises 

 entirely from the mantle {hyperstriatum superius), while the uiider- 

 part {hyperstriatum inferius), arises from the mantle (laterally) as 

 well as from the base of the brain in front of the palaeostriatuni. 

 both parts of the hyperstriatum thus show the fact, that intra- 

 ventricular protrusions of striatal type may originate from the pallium 

 as well as from the base of the brain, as I already pointed out for 

 the primary epistriatum in bony (ishes, and as was pointed out by 

 Elliot Smith for the neostriatum of reptiles", (op. cit. p. 148). 



The arrangement of the blood vessels in the adult bird's brain is 

 in accord with these results based upon ontogenetic studies. Moreover 

 the material employed demonstrates the fact that in the embryo the 

 lamina medullaris externa "is a place of predilection for blood 

 vessels", (op. cit. p. 146, cf. figs. 11, 12, 13). 



e. Summary of the Fibre-Tracts of the Fore-Brain. 



The following tracts have already been discussed. 



1. Ventral forebrain bundle. 



2. Olfacto-habenular tract. 



3. Superior telencephalic commissure. 



4. Pallial commissure. 



5. Fronto-episti'iatic tract. 



6. Interepistriatic commissure. 



Three bundles connect the forebrain with the mesencephalon. 



1. Tractus strio-mesencephalicus. This tract, which connects the 

 mesostriatum with ihe ?iuc/f».« .syJiVi/or/Ju'*- (fig. Xll), can be recognised 

 in its course through brain stern (flg. X). 



2. Tractus occipito-mesencephalicus. The occipito-meseiicephalic 

 tract takes origin in the archistriatum and ends m i\\e nucleus spiri- 

 formis and neighbouring gray matter of the mesencephalon. 



It enters the brain stem ventral lo the anterior commissure arching 



