CAUSES OF QUICK AND SLOW RESPIRATION. 



327 



The respiratory 

 movements 

 maj be ren- 

 dered slow by 



^Diminiebed excite- 

 ment of respiratory 

 centre. 



Nervous influences. 



Diminished venosity of blood. 

 Action of drugs. 



'"Slight irritation of cutaneous 



nerves. 

 Action of voluntury centre. 

 Paralysis of vagi. 

 -} Irritation of superior laryngeal 

 nerves. 

 Irritation of inferior laryngeal 



nerves. 

 Irritation of nasal nerves. 



If the drug to be experimented on be injected subciitaneously 

 or into the veins, the actions on the respiratory centre and 

 on the vagi are the chief points which require attention; 

 but if we are experimenting with a vapour, its local action 

 on the nasal, laryngeal, and possibly, also, on the pharyngeal 

 nerves (Brown-Sequard, Archives of Scientific and Practical 

 Medicine, p. 94) must be carefully attended to, as it may 

 greatly modify its general action on the respiratory centres. 

 Thus Kratscbmer has found {op. cit.) that tobacco smoke 

 inhaled by a rabbit through its nostrils, or blown upwards 

 into the nasal cavity from an aperture in the trachea, will 

 cause arrest of breathing in a state of expiration from the 

 irritating effect of the vapour on the nasal branches of the fifth, 

 while it has no such effect when blown into the lungs. 

 Ammonia, when inhaled, also arrests the respiratory move- 

 ments in the same way; but Knoll {Sitzungs-ber. der Wien. 

 Acad., voL Ixviii, Abt. 3, p. 255) has observed that, if it be 

 blown into the lungs, while the nostrils are carefully protected 

 from its influence, it causes accelerated and shallow breathing, 

 alternating with slow and deep respirations, and occasional 

 stoppages in the position of expiration, obviously from its 

 action on the different fibres of the vagi. AVhen injected into 

 the blood, it causes, according to Funke (Pfliiger's ArcMv.^ 

 vol. ix, p. 436), various alterations in the respiration, which are 

 not easy to analyse, but it certainly seems to excite the respira- 

 tory centre ; but the use of carbonate of ammonia in broncliitis 

 has long been familiar to the medical profession. 



The movements of respiration are not only more easily 

 counted than in any otlier way, but their depth, and the 



