THE STRUCTURE OF THE ELEMENTARY TISSUES. 107 



corpuscles are spherical in shape, and receive many nervous fibres which 

 wind through the corpuscle, and end in the free extremities (fig. 113). 



4. Tactile Menisques. In different regions of the skin of man, one 

 meets, in the superficial layers and in the Malpighian layers, nerves 

 which, after having lost their myeline sheath, divide and subdivide to 

 form extremely beautiful arborizations. The branches of these arboriza- 

 tions are flattened down, forming the tactile menisques. These men- 

 isques, which simulate the form of a leaf, represent a mode of terminal 

 nervous arborization (Eanvier). 



5. The corpuscles of Golgi are small terminal placques placed at the 

 union of tendons and muscles, but belonging more properly to the tendon. 



Fig. 114. A termination of a medullated nerve-fibre in tendon, lower half with convoluted medul- 



lated nerve-fibre. (Golgi.) 



They are fusiform in shape and are flattened upon the surface of the 

 tendon close to its insertion into the muscular fibres. They are composed 

 of a granular substance, enveloped in several concentric hyaline mem- 

 branes which contain some nuclei. The nerve-fibre passes into this 

 little corpuscle, splitting itself up into fine terminals. The corpuscles 

 of Golgi are believed to be related to the muscular sense (fig. 114). 



In addition to the special end-organs, sensory fibres may terminate in 

 plexuses, as in the sub-epithelial and intra-epithelial plexus of the 

 cornea. 



The Neuroglia. 



The neuroglia, while not a nervous tissue, is closely mingled with it 

 and forms an important constituent of the nervous system. It consists 

 of cells giving off a fine network of richly branching fibres. Neuroglia 

 was at one time considered to be a form of connective tissue, and it is 

 in its functions strictly comparable to the connective tissue which sup- 

 ports the special structures of other organs, like the lungs and kidney 

 (fig. 116). It is, however, derived from the epiblastic cells, i.e. 9 the 

 same cells from which the nerve-tissue proper also develops. In the 

 adult animal the neuroglia-tissue is composed of cells from which are 

 given off immense numbers of fine processes. These extend out in every 



