42 BULLETIN OF THE LABORATORIES 



In front of the corpora ciuadrigemina is a strong posterior commissure. 

 The lower portion of the third ventricle pertaining to the tuber cin- 

 eriim is bounded behind by the tuberculum mamillare and the substan- 

 tia cinerea posteriora, in front by the thin grey lamella rising to the cor- 

 pus striatum, the lamina ierminalis. 



The copora striata are pear shaped bodies, the anterior portions of 

 which are connected by the septum pelliuidum, which, in turn, is con- 

 nected, with the lamina terminalis. The septum is perforated by the 

 fibres of the commissure anterior. The lower surface of each hemi- 

 sphere is provided with a \)roii\\:)tY2i\-\(ZQ ox processus pyn'/ormis (in reali- 

 ty produced by the fold of the hippocampus) which is separated by a 

 sulcus {thinaiis ^wd pflst-rhina/is) from the remainder of the cortex. 

 From the anterior or narrow portion of this pear shaped area extends 

 the olfactory lobe. 



Removal of successive horizontal slices of the hemispheres exposes 

 the cal/osum, which is medianly connected by a considerable adhesion 

 with the cornua am^aonis. Each lateral ventricle is a cavity lying 

 between the corpus striatum and septum pellucidum in front. and be- 

 tween the corpus striatum and cornu ammonis below and medianly. 

 After suitable preparation, fibres can be seen crossing below the callos- 

 um and ending in the groove between the thalamus and striatum and 

 probably representing the posterior limb of the fornix. 



Cranial Nerves I and II, as usual. T\\t oculomotor (III) springs 

 from the median surface of the crura, just behind the corpus mamillare. 

 The trochlearis (IV) originates as a fine fibre from'the horizontal part 

 of the valvula cereb^Ui, imn^iiately behind the quadrigemina. The 

 trioz'fiinu^ (V) arisen jusc posterior to the p3ns and is composed of a 

 lateral portio major and median portio minor. The abducens (VI) 

 emerges near the median line, near the posterior margin of the pons. 

 The facial (VII) emerges obliquely from the medulla behind the pons 

 upon the corpus trapezoideum. The auditory (VIII) springs from the 

 lateral surface of the tuberculum laterale, immediately behind the tri- 

 geminus. The glossopharyn^real (IX) is a root of about three bundles 

 springing from the lateral surface of the medulla behind the tubercu- 

 lum laterale, forming a small ganj^lion. The vagus (X) consists of 

 several bundles, forming an arch along the lateral surface of the me- 

 dulla, the lowest bundle being continuous with the accessory {YA)^ fibres 

 of which extend back as far as the third or fourth spinal nerves. The 



