6 4 



Scientific Proceedings (63). 



It is interesting to note that while the chromatin of the somatic 

 cell (the one in which the diminution process occurs) is affected 

 by the treatment with the carbon dioxide, the chromosomes of the 

 " Urgeschlechtszelle " are perfectly normal. 



42 (974) 



Apnea as an after-effect of pulmonary distension and its de- 

 pendence upon the vagus nerves. Demonstration. 



By T. S. Githens and S. J. Meltzer. 



[From the Department of Physiology and Pharmacology of the Rocke- 

 feller Institute for Medical Research.] 



In recent years the conception became dominant, due especially 

 to the investigations and teachings of Haldane and his pupils, 

 that apnea as an after-effect of distension of the lung is essentially 

 of chemical origin, due to a reduction of C0 2 in the blood cir- 

 culating through the respiratory center; this has been designated 

 as apnea vera. It was recently stated that there is no experi- 

 mental evidence for a possible claim that "true apnea" could 

 depend exclusively upon the intactness of the vagus nerves. At 

 this meeting G. and M. demonstrated the following three facts. 

 (1) A fairly prolonged and complete apnea followed a short dis- 

 tention of the lungs in dogs without any previous artificial respira- 

 tion ; the duration of the apnea depended upon the degree of pres- 

 sure used for the distension (Meltzer's pleural canula was used for 

 the graphic presentation of respiration). (2) The same apneic 

 after-effect was obtained when the air used for the distension of 

 the lungs contained 5 per cent. CO2. (3) No such apneic after- 

 effect could be obtained after both vagus nerves were cut. 



These experiments demonstrate that the mere distension of 

 the nerve endings of the pulmonary vagus without the aid of a 

 chemical factor (acapnia) is capable of producing a prolonged apnea 

 as an after-effect of the mechanical stimulus. The restriction of 

 the use of the term "true apnea" for a condition produced exclus- 

 ively by chemical changes does not seem to be well founded. 



