Lung Volume without Forced Breathing. 141 



indeed for the sick. 1 These two fruits have been classed for a 

 long time as antiscorbutic agents. It is therefore important to 

 determine as near quantitatively as possible their antiscorbutic 

 potency in the raw state and after subjection to heat treatment 

 such as is ordinarily employed in the preservation and cooking of 

 these materials. 



Experiments have been conducted on guinea pigs on a basal 

 diet adequate in all respects except the antiscorbutic vitamine. 

 To determine the presence or absence of this latter factor in raw, 

 dried and cooked apples and bananas a daily allotment of these 

 foods has been fed to the animals. We have found that a per 

 diem dose of 10 grams of raw apples or of bananas will protect a 

 guinea pig against scurvy for three months. On the contrary an 

 equivalent amount of these foods cooked at ioo° C. for fifteen 

 minutes or dried at 55-60 0 C. (with the exception of apples which 

 showed some antiscorbutic potency) or dried at 55-60 0 C. and 

 cooked for fifteen minutes at 100 °C. will not protect the animals 

 against scurvy. 



67 (1649) 



The determination of lung volume without forced breathing. 



By DONALD D. VAN SLYKE and CARL A. L. BINGER. 



[From the Hospital of The Rockefeller Institute for Medical Research.] 



The dilution method for determining lung volume, invented 

 by Davy and modified by Bohr and his coworkers, and recently 

 by Lundsgaard and Van Slyke, rests on the principle of mixing 

 the air in the lungs with a known volume of foreign gas (H 2 or 0 2 ), 

 and calculating the air content of the lungs from the extent to 

 which either the foreign gas or the nitrogen of the lung air (Lunds- 

 gaard and Van Slyke) is diluted. This method yields satisfactory 

 results when the subject can breathe deeply, so that 4 or 5 respira- 

 tions cause complete mixture of the lung air with the diluting gas. 

 When the subject, however, because of weakness or respiratory 

 disturbance, cannot greatly increase the depth of his respirations, 

 so much time is required for complete mixture that volume changes 

 due chiefly to absorption of oxygen make accurate results unob- 

 tainable. 



1 Myers, V. C, and Rose, A. R., /. A. M. A., 1917, lxviii, 1022. 



