102 Society for Experimental Biology and Medicine. 



inal wall. This was connected with a water manometer arranged 

 to record by a float and marker upon a smoked paper. 



In dogs the pressure varied from 2-45 mm. of water above 

 atmospheric, i. <?., positive. 



In cats from 2-20 mm. positive. 



In rabbits from 2-25 mm. positive. 



In calves from 2-10 mm. positive. 



The causes of this persistent but fluctuating positive pressure 

 within the free peritoneal cavity are the tone of the muscular walls 

 of the peritoneal cavity, including the diaphragm and the pelvic 

 floor. 



The contraction of the diaphragm is the chief, if not the only 

 factor in the normal rise in pressure during inspiration. 

 Debilitated states show a low pressure. 



Ether anesthesia causes a gradual drop in pressure until with 

 complete loss of muscular tone, the pressure reaches zero. 



Curare likewise causes a progressive fall to zero pressure. 



Asphyxia develops great rises in pressure during inspiration 

 until muscular relaxation allows a drop to zero just before death. 



Excessive pressure artificially produced within the peritoneal 

 cavity causes death from cardiac failure before the obstruction to 

 respiratory excursion has developed a marked asphyxia. 



The pressure is the same at all points of the peritoneal cavity, 

 and is subject to identical variations wherever the recording trocar 

 is placed. 



The physiological function of these pressure conditions seems 

 to be chiefly in assisting the circulation of blood and lymph, 

 thereby playing an important role in the processes of absorption 

 and elimination which take place within the abdomen. 



Clinical observations in diseased conditions are under way. 



