(364 ) 



somewhat the excitability of the psycho-motor centres -). "We stated, 

 that ether, in diminishing the irritability of those centres ^), causes all 

 those irregularities to disappear. 



"We also observed that acoustic and optic impressions were in many 

 cases the perceptible causes of these sighs, and it is known in human 

 pathology, that a general stimulation of the human cortex (menin- 

 gitis, tumour of the frontal lobe) may occasion similar sighs. 



So there is room for the opinion, that morphia exercises the same 

 influence on the point 16 of the frontal cortex as on the other 

 psycho-motor centres, and that our experiments were made on dogs, 

 whose inspiratory functions were increased by a tonus, proceeding 

 from the cortex of the brain. "We notice at the same time two diffe- 

 rent effects upon those inspiratory functions, 1" the deep inspira- 

 tion, 2° the quickening of rhythm. 



The influence of the operation. 



Of still greater importance is the effect of the operation on the 

 animal, after the increasing (by morphia) of its sensibility to influences 

 which promote inspiratory effects. 



Nerves (the optic Nerve and two branches of the trifacial Nerve) 

 are exposed and cut through, and so are stimulated mechanically. 



This stimulation changes the respiration. 



Effect of the faradic excitation of the optic Nerve 

 upon the Respiration. 



The tracing of the respiration registered during the faradic excita- 

 tion of the optic Nerve (fig. 3 N. opt.) is a very characteristic one. 



When stimulating with a very weak current (12 cm. distance 

 between the two coils) a quick and very deep inspiration is piodu- 

 ced, immediately followed by a lengthened, suppressed expira- 

 tion. The stimulus not being of too long duration, the suppression 

 of the expiration lasts as long as the stimulation, and sometimes 

 even longer. 



After stimulating with moderate currents (10 — 6 cm. distance 

 between the two coils) the tracing of respiration is that Avhich is 

 reproduced in fig. 3. A series of quick respirations is superimposed 



1) HiTziG 1. c. p. 38. 

 ^) Hjtzig 1. c. p. 39. 



