76 ANIMAL BIOLOGY. [Parti. 



acteristic, great numbers of nerve cells of various shapes 

 and sizes, but generally multipolar and stellate, and larger 

 in the ventral of the two divisions or cormia into which 

 the grey matter of each side of the cord is divided. In 

 both white matter and grey matter the fibres and cells 

 are imbedded in a supporting connective tissue (neuroglia) 

 which forms a very large proportion of the grey matter. 

 This consists of (1) homogeneous semi-fluid matrix, (2) of 

 a network of delicate fibrils, and (3) of branched nucleated 

 cells. 



The brain is composed of white matter and grey matter ; but 

 in the cerebral hemispheres and cerebellum the grey matter is 

 external to the white. 



10. Nerve Endings. Nerve fibres terminate peripherally in 

 various ways. In the epithelium of the skin the axis fibre breaks 

 up into a network of fibrillae lying in the interstitial substance 

 between the cells. In striped muscle the network into which 

 the axis fibre breaks up encloses nuclei of various shapes, and 

 is known as an end-plate. And in connection with the special 

 sensations there are specialised terminations of the sensory 

 nerves. 



(a.) Touch. In sections of a rabbit's or a cat's lip, the deeply 

 implanted hairs (mystaces) will be seen to terminate in enor- 

 mously enlarged bulbs, with which nerve fibrillse enter into 

 close connection. Such hairs may be regarded as special sense 

 organs. In the skin of the human finger the sensory nerves are 

 in connection with pacinian corpuscles, large oval bodies, in which 

 the central nerve thread is surrounded with a number of coats, 

 onion-fashion (Fig. 30, iii.). Somewhat similar corpuscles are 

 found in the tongue, mesentery, and elsewhere. They may be 

 tactile, but their function is not certainly known. Much smaller 

 corpuscles in the papillae beneath the epidermis of the human 

 finger are undoubtedly tactile. 



(b.) Taste. On each side of the tongue of a rabbit is a plaited 

 patch, the so-called papilla foliata. Fig. 27, i. shows a portion 

 of a section across the folds of this patch. On the adjacent 



