THE NERVOUS SYSTEM. -l.'ii) 



number in a close plexus of fine fibres of 00001 — 0001 2'"; 

 and cells, in other respects exactly similar, though not quite 

 of the same size, also exist in the corpus mammillare, 

 likewise intermixed with very numerous fibres of the finest 

 sort ; there are other still smaller cells of 0-008 — 0-012'", 

 for the most part with only two processes, in the tuber cinereum. 

 The hypophysis cerebri contains, in its anterior, reddish lobe, 

 no nervous elements; but rather, according to Ecker (art. 

 ' Blood-vascular Glands/ in Wagner, ' Handw. d. Physiol.'), 

 the elementary tissues of a blood-vascular gland ; that is to say, 

 a vascular stroma of connective tissue, in the interstices of 

 which, lie vesicles (cells?) measuring 0*030 — 0090 mra , con- 

 taining sometimes only nuclei, and a fine granular substance, 

 sometimes distinct cells, in older persons also colloid-like 

 masses. The posterior, smaller lobe consists of a fine 

 granular substance, with nuclei and blood-vessels, and also 

 contains fine, varicose nerve-fibres, which, like the vessels, 

 descend from the infundibulum. 



§117. 



Hemispheres of the Cerebrum. — The white substance of the 

 hemispheres of the brain consists entirely of nerve-fibres, of 

 0-0012 — 0-003'", on the average 0-002'" in size, without any 

 admixture of grey substance. These fibres, of whose special 

 course, we, as yet, know extremely little, never form plexiform 

 interlacements or fasciculi, but all run in parallel, and most 

 generally, straight lines, and undoubtedly proceed from the 

 corpus cal/osum and ganglia of the cerebrum as far as the 

 superficial grey substance, whilst it must remain unde- 

 termined whether, in their course, they divide or not. But 

 besides these fibres, omitting also the commissura anterior, 

 the fornix, and the origin of the optic nerves, the hemispheres 

 contain others crossing the former at right angles. I have 

 found these fibres, in the first place, on the outer side of 

 the corpus striatum, in which situation they are to be referred, 

 in part, to the fibres which enter the corpus striatum from the 

 hemispheres and terminate in it ; perhaps, also, in part, to the 

 expansion of the corpus callosum in the inferior lobes ; and 

 secondly, in the most superficial layer of the white substance, 

 near the grey cortical substance, where they occur in not 



