RESPIRATION 



271 



stimulation of the inferior laryngeal causes closure of the 

 glottis, for although it supplies both abductors and adductors, 

 the latter prevail. With weak stimulation, and in young 

 animals, the abductors carry off the victory, and the glottis 

 is opened (Risien Russell). 



Interference with the connections on one side, between 

 the higher cerebral centres and the medulla oblongata, as by 

 rupture of an artery and effusion of blood into the posterior 

 portion of the internal capsule (giving rise to hemiplegia, 

 or paralysis of the opposite side of the body), is not followed 



F IG . 99. DIAGRAM OF VOCAL CORDS IN PARALYSES OF THE LARYNX. 



a, Paralysis of both inferior laryngeal nerves. The vocal cords have taken up the 

 ' mean ' position, b, Paralysis of right inferior laryngeal nerve. An attempt is being 

 vnade to narrow the glottis for the utterance of sound. The right cord remains in its 

 4 mean ' position, c, Paralysis of the abductor muscles only, oo both sides. The 

 cords are approximated beyond the ' mean ' position by the action of the adductors. 



by loss of voice ; the laryngeal muscles on both sides are 

 still able to act. 



PRACTICAL EXERCISES ON CHAPTER III. 



[ ; . Tracing of the Respiratory Movements. (a) Set up the 

 ingement shown in Fig. 100, and test whether it is air-tight. 

 Have also in readiness an induction machine and electrodes arranged 

 for an interrupted current. Anaesthetize a rabbit with chloral 

 (Experiment 24, p. 190), or a small dog* with morphia and ether 



* If a large dog is used the bottle may be omitted, the tracheal cannula 

 being connected with the stem of a T-tube. One end of the horizontal 

 limb of the T-tube is connected with the tambour ; the other is provided 

 with a rubber tube which can be partially closed by a screw clamp to 

 regulate the excursion. 



