( 370 ) 



the opposite fore-log caused by faradisation of the psyclio-inotor 

 centre of the foreleg. 



Occasionally the compensation-movements may be seen, even 

 without the pre-existence of the arrest itself (Fig. 11 lower tracing). 



Exceptionally, the mechanism of compensation is not brought 

 forth, and in two cases the dog died from the shock, respiration 

 being arrested in expiration. In the cases, in which this event took 

 place, the inspiratory functions had been injured by preceding expe- 

 riments of long duration. 



It is clear, that these expiratory effects are due to the stimu- 

 lation of the olfactory bulbus, tractus and lobus, consequently of 

 a nerve-tract, not of a centre. It may be conceived, that the dog, 

 as soon as strong olfactory impulses reach him, arrests the respira- 

 tion in expiration, to prevent his smelling more. Then prudently, 

 with irregular, superficial respirations, the thorax is brought into an 

 inspiratory position an<l as soon as the danger seems past, he restores 

 his respiration with deep sighs and long, deep inspirations. The 

 tractus olfaelorius answers faradic excitation by expiratory effects. 



The difference between our results and those of Spencer, which 

 will make further experiments necessary, may perhaps be due to 

 the fact, that Spencer worked with ether-narcosis. 



DESCRIPTION OF FIGURES. 



Fig. 1. Morpliia-sigli of a dog. 

 1 is the zeroline. 

 3 is the tracing of a tuning-fork of 3 vibrations per second. 



3 is the tracing of the movements of the thorax registered with the pneu- 

 mograph of Marey. 



4 is the tracing of the respiration registered from the trachea. 



Fig. 3. Morphia-sigh with quickened respiration superimposed upon the pluise of 

 expiration. 



1 is the zeroline. 



2 is the tracing of a tuning-fork of .5 vibrations per second. 



3 is the tracing of the movements of the thorax registered with tlie pneumo- 

 graph of Marey. 



4 is the tracing of the pulsation of the arteria femoralis. 



Fig. 3. Effect upon respiration during faradic excitation of tiie optic Nerve and 

 during that of the first branch of the fifth Nerve. 



1 is the tracing written b_y the electric signal, noticing the moment of 

 excitation. 



2 is the tracing of the tuuing-fork of 2 vibrations per second. 



3 is the tracing of the movements of the thorax registered with the pneumo. 

 graph of Mabey. 



4 is the tracing of respiration registered from the trachea (in all the 

 following figures, the ciphers 1 — i have the signification here mentioned). 



