CHAP. XXIIT.] OF THE HUMAN BRAIN. 467 



The great ganglion cells encroach upon the outer border 

 of the next stratum, which is the so-called ' granule layer.' 

 Here are massed together a multitude of corpuscles from 

 TCK)"O * "2 ~5lTo ^ an * nc k i n diameter, very similar to 

 those more sparingly scattered through the outer layer. 

 The inner process of each large ganglion cell is said to be 

 single and undivided, but as it is very fine it is soon lost 

 to view in the dense ' granule layer ' into which it passes. 

 The mode of connection of the central stem of white fibres 

 with the granule layer and with the elements lying out- 

 side it, is at present very uncertain. ' Granules,' or cor- 

 puscles of the same kind, are also, though more sparingly, 

 scattered through this white substance. 



It seems most probable that some of the fibres in each 

 stem of white substance are * afferent,' and that others 

 conduct ' efferent ' impressions or impulses. The former 

 fibres may divide in the ' granule layer,' so as to come 

 into relation with two, three, or more of the great ganglion 

 cells ; and the outgoing stimuli may pass from these 

 groups of cells through their ramifying branches in the 

 outer layer, and thence through continuous rootlets of 

 ' outgoing ' fibres which, coalescing as they go, pass 

 through the ' granule layer,' and away through the stem 

 of white substance. 



This latter is a hypothetical arrangement, but one which 

 seems to the writer to be most in accordance with the 

 actual structure of the grey matter of the Cerebellum. 



7. The Central Connections of the Olfactory and 

 Optic Peduncles, as well as of other Cranial 

 Nerves. 



The Olfactory Peduncles or 'tracts,' and the Optic 

 Peduncles or ' tracts ' are generally regarded as some- 

 thing different from ordinary nerves. They ure looked 



H H 2 



