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APPENDIX 



11. THE RESPIRATORY CANNULA. 



In experiments involving the opening of the thoracic wall, artificial 

 respiration must be maintained. A bellows worked by hand or by 

 machinery will be required. The valves of the bellows open inward 

 only; therefore, some vent or escape must be furnished, otherwise the 

 air pressure would rise too high within the lung and the animal would 

 breathe the same air repeatedly. 



To accomplish the desired result and to avoid the last-mentioned 

 difficulties Prof. Ludwig long ago devised the respiratory cannula 

 shown in Fig. 87, A. 



FIG. 87 



B 



Respiratory cannulae : A, that of Ludwig, metallic; B, that of the author, of glass. 



If one does not have at hand a Ludwig respiratory cannula he may 

 quickly and easily prepare one from glass that will answer all purposes. 

 Several of these of different sizes should be prepared so that when 

 needed one may select a size best fitted to the animal under operation. 

 Fig. 87, B, shows the construction of the glass respiratory cannula. 



12. TAMBOURS (RECEIVING AND RECORDING). 



Next to the kymograph the tambour is the most important piece 

 of apparatus in the physiological laboratory. They are used almost 

 daily and in most observations of changing form or pressure. Each 

 completely outfitted table should have the recording tambour in three 

 sizes and receiving tambours of various shapes and construction. 



The recording tambour must vary in size according to the desired 

 excursion of the middle of the membrane, and that, in turn, will vary 

 with the amount of air involved in the to-and-fro movement in the 

 pressure tube and tambours. If one is to trace the movements of 

 the human thorax in respiration he will want a capacious receiving 

 tambour and a large recording tambour, while the tracing of a 

 sphygmogram requires a very small recording tambour. 



The recording tambour consists essentially of a shallow pan 1 to 

 6 cm. in diameter, from which a tube leads to the pressure tube 



