Carbon Dioxid Dissociation Curve. 



5 



i pq = x-w, etc., 

 a\ - [(2W + 2(* 2 ) - 2X(WX))]/N - i\ q , 



and similarly for o^, <7,- rs 



The product moment for any two growth increments, say 

 i pq and i r8 , is 



2(i Pi ir 8 ) = 2(wy) - 2(ws) - 2(*y) + 2(3:2). 



In the special case in which three consecutive stages, say w, x, y, 

 are involved we write 



2(w 5 r) = X(wx) - 2 (wry) + 2(*y) - 2(x 2 ). 



Problem 3. — To determine the correlation between the size 

 of the organism at any stage and any growth increment. 



The notation of problem (2) may be used. The physical 

 constants for the growth stages and growth increments have 

 been given. The product moments are 



2(w P3 ) = 2(>x) - 2(> 2 ), 2(xi qr ) = 2 (ay) - 2(x 2 ), 

 X(wi qr ) = 2(wy) — 2(wx), 2(wi r8 ) = 2(wz) — 2(wy), etc. 



Illustrations of applicability will be given elsewhere. 



3 (1585) 



The carbon dioxid dissociation curve and the arterial and venous 

 carbon dioxid tension of human blood in health and in disease. 



By John P. Peters, Jr. and David P. Barr. 



[From the Russell Sage Institute of Pathology and the Second Medical 

 Division of Bellevue Hospital, New York, N. Y.) 

 A method for the direct determination of the carbon dioxid 

 tension of human arterial and venous blood has been applied to 

 a series of normal and pathological subjects. The method is 

 similar to one recently described by Means, Bock and Wood- 

 well 1 for the determination of arterial carbon dioxid tension, but 

 was developed and applied by us independently before the ap- 

 pearance of Means' paper. It is a development of the work of 

 Henderson and Haggard 2 on the " Hemato-Respiratory Func- 



1 Means, Bock and Woodweli, Transactions Am. Assn. Physicians, 1920. 

 3 Henderson and Haggard, Journ. Biol. Chem., 1919, xxxix, 163. 



