( 334 ) 



ventral branches of the spinal nerves were sought. In most cases 

 these were caught up and torn off together with the connecting 

 branches of the N. sympathicus. 



In all cases the visible consequence of these operations consisted 

 constantly in the appearance on the skin of a more or less sharply 

 defined dark tield, i.e. darker than the surrounding skin. Distribution 

 and extent of these dark fields were dependent on the place in the 

 segmental arrangement of the sectioned nerves and on their number. 

 The shape of these fields was always identical, being that of a band, 

 beginning in the dorsal marginal fin, going somewhat obliquely 

 cranialward to the lateral line of the organ of sense, and thence 

 somewhat obliquely caudal ward towards the ventral marginal fin, 

 wherein it terminated. Thus much for the shape and the general 

 distribution of these zones. As regards their extent, the following 

 may be stated. After destroying the connecting branch of one single 

 spinal nerve I never observed any plainly visible change in the 

 colouring of the skin. After destroying the connecfiiii; branches of 

 two consecutive nerves, usually a narrow, not very dark zone was 

 observed, that might be not easily defined. Only when three conse- 

 cutive branches were destroyed, there appeared a plainly visible, 

 sharply defined dark zone. 



r-rsysS y/ /7// 







# 



* ^^^ 



Fig. '2. 'J 



Rhomboidichthys mancus, dark zone appearing alter cutting through three 



spinal nerves and the sympathetic connecting branches. 



If more than three branches were 1 destroyed, there was found a 

 dark zone, identical as to shape and position, only broader. If after 

 ,i first section of viz. three branches, still another couple of brandies, 



>) This figure and tig. 3, 4, 6, 7, 8, 'J are reproductions of photographies 

 counterdrawn in outline. 



