( 3G7 ) 



of the expiration — our sigh — , 2° as a permanent and maxi- 

 mal inspiratory position of the thorax (Spencer's ovor-inspiratcry tonus). 

 The excitation of these nerves makes it possible to distinguish and 

 separate the two inspiratory effects. The optic Nerve, when excit 

 od with a very weak current only produces the rise of the sigh, 

 the excitation of the first branch of the fifth Nerve in that case 

 quickens respiration. Somewhat stronger currents generally call 

 forth both effects (Spencer's over-inspiratory clonus) together. A 

 very strong current may give in both cases a permanent inspiratory 

 effect. At the same time the tracing of respiration during the exci- 

 tation of the optic Nerve, can in no case be confounded with one, 

 written during the excitation of the first branch of the fifth Nerve. 



If the cortex of the brain is excited at the point 16 of our dia- 

 gram the same order of effects is produced. Weak currents cause 

 acceleration of rhythm, i) moderate currents deep inspiration, length- 

 ened and suppressed expiration, often with a quick rhythm of res- 

 piration superimposed in the tracing, ^) strong currents may produce 

 an over-inspiratory tonus. '•') 



The same effect is produced as soon as the side wall of the 

 third ventricle is stimulated. We fully confirmed Christiani's 

 results on this subject, as opposed to those of Knoll ^), Tlie 

 excitation of a spot in the side wall of the ventricle, situated under 

 the commissura posteiior, produces inspiratory effects. Again weak 

 currents cause acceleration of rhythm, moderate currents cause deepe- 

 ning of inspiration combined with acceleration, strong currents pro- 

 duce a forced, permanent inspiration (Fig. 5). It seems probable too, 

 that in this case, no centres are excited, but nerve tracts ori- 

 ginated from the cortex cerebri in the region of point 16 of our 

 diagram. 



Our operation often causes the accelerated type of respiration, by 

 mechanical excitation of the Nerves. This is nearly always the case, if 

 it is necessary to remove the contents of the orbita, in order to make 

 room for the exposure of the frontal and basal parts of the brain. 



The ophthalmic artery and the ophthalmic vein must bo tied and 

 often it is impossible to tie the ligature, without taking the optic 



') Winkler 1. c. fig. XXIV. 



=) Winkler 1. c. fig. XXV and fig. XXVIII, 



') Winkler 1. c. fig. XXVI and fig. XXVII. 



*) Prof. Ph. Knoll. Beitriige zur Lehre von der Athraungs-Innervalion. 6'<' Mitth. 

 Zur Lehre vom Einflusz des centralen Nerveusystems auf die Athmuug. Sitzungsber. 

 d. K. Ak. d. Wissensch. in Wien. Bd. XII. Abth. III. S. 283. 



