50 



of the dendrites, the tit^roid-bodies become elongated. These 

 do not reach far alon^ the dendrites, however. 



i. Termination of General Cutaneous fibres. — The nerve- 

 fibres of the general cutaneous system are distributed to the 

 skin of the head without the intervention of special] ^•ed nerve- 

 endings. This sensory system has components in the V, IX, and 

 X nerves. There are two principal central stations for these 

 fibres: the general cutaneous nucleus, and the dorsal cornu of 

 the spinal cord through the medium of the spiral V tract. The 

 two termini are really not essentially different, however, 

 since the general cutaneous nucleus and the dorsal cornu are 

 morphologically continuous structures. 



Fibres which have their termination directly in the gen- 

 eral cutaneous nucleus may pass into their arborizations in 

 relation to each of several groups of neurones. What is prob- 

 ably the chief mode of termination is shown in Fig.5,g.c.f., 

 where the fibre is seen entering the tangle of the substantia 

 gelatinosa. At no other point in !/ustelus is there such a 

 bewildering maze of nervous processes as that presented by the 

 neurones here. 3o far as structural features may be interpre- 

 ted, it would seem that the substantia gelatinosa is well adapt- 

 ed for the reception of the most delicate sensory impressions. 

 The large number of arborizations found here indicates the real 

 importance of the group. 



Terminations are also to be traced in connection with the 



