126 MANUAL OF HISTOLOGY. 



penetrates it at a prominence (Doyere* s eminence). From tliis 

 point it divides into fibrils, which form delicate networks, and 

 one, or possibly two filaments will be seen to enter an irregular 

 body placed in the centre of the fibre. This body is highly 

 nucleated, and may without much difficulty be distinguished 

 from the muscle nucleus, which lies either on the bundle or in 

 it. This body is called the motor ial plate. It is not certain, 

 however, that the ultimate fibrils actually end there, for in 

 some instances one is in connection with one side, and one with 

 the other. Yaricosities are described in the primitive fibrils 

 when osmic acid or chloride of gold is used. 



Gschleiden, of Breslau, one of the most recent writers on 

 this subject, has traced (in the leech) the ultimate fibrils to the 

 cement substance between the contractile muscle-corpuscles 

 (unstriped muscular tissue). He never saw them end in plates 

 or in networks. Ganglion-cells are closely attached to the 

 fibres near their termination, and they may be unipolar, bi- 

 polar, or even multipolar, the former being the most numer- 

 ous. 



Termination of nerves in epithelial bodies has been de- 

 scribed by a good many observers. The demonstration of such 

 endings, however, is extremely difficult. The ultimate fibrils 

 are liable to be confounded with elastic tissue, possibly with 

 connective-tissue fibres. To be quite sure of their character 

 they should be traced into connection with nerve- trunks, on 

 the one hand, or ganglionic bodies on the other. 



Connective tissue of nerves. In our description we have 

 adhered to the idea that the sheath of Schwann is the one that 

 immediately incloses the medulla, without any intervening 

 substance. Ranvier has called the first sheath, exterior to 

 Schwann' s, " the sheath of Henle. " (Fig. 43,. e.) 

 The term perineurium is often applied to the sheaths of the 

 funiculus or bundle. The connective tissue separating the 

 funiculi in a large trunk has been called the endoneurium, 

 while epineurium is the great sheath 'of the whole trunk. 

 Each bundle or funiculus, the smallest element that we see in 

 making a gross dissection of a nerve, is covered with one or 

 more layers of endothelium, forming a special sheath. These 

 funiculi do not run parallel without anastomosing, but two, 

 joining, form a third, which again divides. 



There is much practical difficulty in the way of giving pre- 



