xxii Journal ok Comparative Neurology. 



origin of the congruous. Just as natural selection accounts for organic 

 development by the elimination of the unfit, but makes no pretence, or 

 should make none, to account for the origin of the fit (which is a distinct 

 problem), so do I suggest that natural development results from the con- 

 stant elimination of the incongruous; but I make no pretence that it 

 accounts for the origin of the congruous. It is a theory of survival, not 

 of origin. — Prof. C. Lloyd Morgan, Univ. College, Bristol. 



Origin of the Acoustic Nerve, i 



Summary, i. Deiters', the dorsal, and Bechtegrew's nuclei are not 

 niduli of origin of the acoustic, and the cells belong to Golgi's first type 

 which apparently send fibres into the formatio reticularis. 



2. The ventral nidulus and the tuberculum laterale are centres of 

 origin, the former for the anterior, the later for the posterior portion. 



3. The ventral nidulus consists of two sorts of cells, tlie central 

 portion containing cells similar to centers of origin of nerves, the peripheral 

 elements resembling cells of the spinal ganglia. The former give rise to 

 processes which subdivide in the neuropilem from which the nerve springs, 

 while those of the latter attach themselves at right angles to the root 

 fibres. 



4. From the latter sort also arise fibres which pass fram the ventral 

 nidulus to the corpus tiapezoides and reticulum of the superior olives. 



!;. The posterior root of the acusticus arises by most of its fibres 

 (strias acusticse) from the tuberculum laterale, a few being derived from 

 the ventral nidulus. 



7. In the anterior root there are fibres from the corpus restiforme. 



7. The peripheral part of the ventral nidulus may be regarded as a 

 true spinal ganglion. 



8. The nervous elements are, as Golgi stated, in direct anatomical 

 continuity v\ith each other. 



Metamerism of the Head. 2 



McClure describes the primitive vertebrate brain as composed of a 

 series of segments similar to those which have been identified in embryonic 

 cord and sustaining a similar (i. e. intermediate) positon relative to the 

 provertebrae. The segmental nature of the brain is indicated by a series 



L L. Sala. suir origine del nervoacu.stico. 



2. Journal of Morphology . The Segmentation of the Primitive Brain, 1890. 



