Kjeldahl Method of Nitrogen Determination. 197 



In mechanical shock induced by obstruction to the venous 

 return to the heart, the over-distention is due to a draining back 

 of the blood within the capillaries. In inhibitory shock, the over- 

 distention is due to the sudden discharge of blood at high pressure 

 into the capillaries. In either case, the effect upon the capillary 

 wall is the same, and shock would therefore consist in a general 

 displacement of what might be termed a critical quantity of 

 blood from the arterial to the capillary and venous side of the 

 circulation, a displacement which is therefore accompanied by 

 comparatively insignificant volumetric changes and dependent 

 largely upon a loss of a normally existing tone in the walls of the 

 small venules and capillaries. 



118 (1050) 



On the application of the Kjeldahl method of nitrogen determina- 

 tion to serological problems. (Preliminary note.) 



By Byron W. Barshinger. (By invitation.) 



[From the Department of Bacteriology and Immunity, Leland 

 Stanford Jr. University.] 



Practically no variation in the nitrogen content of rabbit 

 serum (centrifuged) is produced by the usual variations in tem- 

 perature at which the blood sample (sealed) is kept during the 

 initial separation of the serum. Sera separated in the incubator, 

 ice chest and at room temperature are identical, within the limits 

 of the experimental error. 



An increase of as much as 100 per cent, in nitrogen content 

 may be brought about by increasing the length of time the serum 

 is allowed to stand in contact with the clot. This increase is most 

 rapid and most pronounced in samples kept at incubator tempera- 

 ture. 



Variations as great as 40 per cent, may be observed in different 

 samples removed from the same rabbit at the same bleeding. 

 Small consecutive samples drawn at five-minute intervals may 

 show differences as great as 10 per cent. 



Variations as great as 40 per cent, above or below the average 

 may be observed in sera of normal rabbits of the same age, size 

 and breed, kept and bled under identical conditions. 



