4g APPENDIX. 



2. " Without the glottis, the action of the abdominal muscles would be constantly em- 

 ployed in producing respiration : neither compression of the viscera, nor flexure of the 

 trunk could be produced. 



3. " There exists a real co?isensus of action between the glottis and the abdominal 

 muscles, and through this medium, between the glottis and the different reservoirs, the 

 bladder, the rectum, the stomach, and the uterus. 



4. The glottis does not confine its action to the production of the voice ; but by the 

 aid of the sympathetic connexions which unite it to the abdominal muscles, charged to 

 concur in, if not to preside over important functions, it excites the greatest influence on 

 those functions themselves. 



5. Lastly, in the different efforts there is a tendency to expiration, to the produc- 

 tion of which the closure of the glottis is an obstacle." 



IIT. Of the Effects of Respiration on the Circulation of the Blood. The experiments 

 of Haller, Lamure, and Lorry, and subsequently those or Cloquet and Bourdon, have 

 shown, 



1. That, during inspiration, the blood of the vena cava, superior and inferior, is 

 drawn towards the heart. 



2. That, during expiration, the blood is, on the contrary, driven in the same veins, 

 towards the viscera. 



3. That the arterial blood is also driven towards the viscera at the time of expira- 

 tion. 



4. That the alternate motions of the brain is owing to the changes caused by respira- 

 tion in the flow of blood. 



5. That all these charges are but little marked in ordinary respiration ; but that they 

 come very evident in full respirations, and particularly so during great efforts. 



6. Lastly, that, during great efforts the glottis is firmly closed, the air contained hi 

 the lungs is compressed, as well as all the pectoral and abdominal viscera. 



In order to ascertain the precise effects produced by respiration on the venous cir- 

 culation, Magendie instituted a set of experiments from which he draws the infer- 

 ences, that respiration modifies the venous circulation;! by the influence which it 

 exerts on the course of the arterial blood ; 2 by its direct action on the current of 

 blood in the veins That in profound respirations and violent efforts, the circulation ap- 

 pears nearly suspended. 



IV. Of the State of the Lungs during Respiration. The experiments of Dr. Carson 

 have directed the attention of physiologists to the state of the lungs themselves during 

 respiration, and under the various influences to which they are usually subjected either 

 by accident, by operations, or by disease. Dr. Carson had inferred from his experi- 

 ments, that it is possible to collapse one of the lungs, and to retain it in that state, ad 

 libitum, by keeping open the communication between the cavity of the chest and the 

 external air; and further, that upon allowing the opening to close, the lung, in a given 

 time, will recover its wonted function, thereby rendering it practicable, when conceiv- 

 ed necessary, to place the opposite lung under the like discipline. In order to examine 

 the stability of these inferences. Dr. David Williams, of Liverpool, instituted several 

 experiments, in the presence of Dr. Trail an i otliers, which contradict some of the chief 

 positions held by Dr. Carson. After detailing his experiments, Dr. Williams draws the 

 following conclusions from them. 



" 1. That a lung will not collapse from exposure to the atmosphere as long as respi- 

 ration is carrred on by the opposite one, and the auxiliary respiratory powers are not 

 restrained. 



" 2. That a lung possesses for a time, independently of the influence of the dia- 

 phragm and intercostal muscles, if respiration is carried on by the opposite lung, a pe- 

 culiar motive power, the source of which I do not pretend to explain. 



"3. That a sound lung soon regains its full power of expansion, when the pressure 

 of the exterior air is removed. 



" 4. That air freelv and uninterruptedly admitted into both cavities of the chest si- 

 multaneously, through tubes of a certain calibre, will not collapse the lungs, if the auxi- 

 liary respiratory organs are unrestrained. 



