506 TITE NATURAL HISTORY RKYTEW. 



like the lower paii*, far more intimately united with the arciforin 

 fibres than with any special nucleus, such as that of the facial, and 

 consequently attributes to them too ' a co-ordinary influence.' 



Dr. Dean, again, is unwilling to admit the existence of any 

 special connection between the trigeminus (which he always, un- 

 wisely as it appears to us, calls the trificial) and auditory nerves, 

 such as Schroeder van der Kolk contended for ; although he regards 

 the caput cornu, out of which the sensor root of the trigeminus is 

 developed, as a kind of centre of communications for all the nuclei of 

 the posterior columns, spinal accessory, vagal auditory, &c. So, also, 

 with regard to a distinct connection between the auditory and facial 

 nerves, in which Schroeder van der Kolk saw an explanation of 

 certain reflex movements, such as those of the ear, &c., caused by 

 sounds. Dean, while tracing fibres from the auditory nerve into the 

 facial nucleus, cannot finil any direct transition into the cells of the 

 latter, and sees no just ground for Schroeder van der Kolk's theory. 

 In fact, the American anatomist seems to have set his face against 

 most physiological deductions from anatomical data. And there is 

 no doubt that such deductions should always be made with the very 

 greatest caution, especially when one is dealing with the minute 

 anatomy of the nervous centres. In no field of observation are 

 there stronger temptations to make a theory, in none less chance of 

 making the right one. The tables indeed might be turned against 

 Dr. Dean, who shares with most of his fellow-labourers a tendency 

 to see every where the instrument of a ' co-ordinating' power. The 

 ' co-ordinating' theory, however, can never prove very dangerous, for 

 no one can see very clear ■> what it means. On the contrary, it may 

 often be of great temporary use in pre-occupying the ground against 

 usurpers, until, in due time, the rightful owner comes to claim 

 his own. 



Our author has a very interesting chapter on the development of 

 the bodies pointed out L3 Clarke, and named by him the ' Tractus in- 

 termedio-lateralis' and the ' Columnae posteriores vesiculosae.' The 

 spinal accessory and vagus are shown to be connected, as Clarke 

 described, with the extension upwards of both these columns. The 

 relations of the vagus and spinal accessory nuclei to certain longi- 

 tudinal columns, which are continued above into the roots of the 

 trigeminus and below into longitudinal fasciculi intimately con- 

 nected with the tractus intermedio-lateralis, are also carefully traced 

 out. By this means the homology of the sensory, or posterior nen^es 



