PREVIOUS INVESTIGATIONS. 15 



Although Vierordt's methods of sampling and analysis seem very crude, 

 we find that Speck, 47 years later, quotes Vierordt as obtaining values 

 not at all unlike those obtained by himself; 1 in fact, he confirms 

 Vierordt's observations in that he finds the maximum carbon-dioxide 

 excretion about 1 hour after the meal. 



Bticker, 1849. Although Vierordt was on two occasions able to 

 compare directly the values obtained before eating with those obtained 

 immediately after the meal, in the extensive research published by 

 Bocker 2 in 1849 no data were obtained for the post-absorptive condi- 

 tion. His experiments, which were carried out with exactly the same 

 technique as that of Vierordt, are very extended and include the inges- 

 tion of sugar, which was taken in portions usually of 1 to 3 ounces, 

 i. e., about 30 to 90 grams. Occasionally it was taken with honey, 

 but usually with water. 



The method of computation employed by Bocker is somewhat 

 difficult to follow, for while the percentage of carbon dioxide in the 

 expired air found by him is not unlike that commonly found, namely, 

 3.5 per cent, the absolute amount of carbon dioxide excreted per minute 

 is considerably more than that ordinarily found under like conditions, 

 varying in his own case from 445 to 589 c.c. per minute. These results 

 were obtained by multiplying the actual values found by the factor 

 2.51. The found values are much more in accordance with those 

 commonly experienced, namely, from 177 to 235 c.c., than those ob- 

 tained by means of the factor. 



From these imperfect experiments Bocker concludes that after the 

 ingestion of sugar the amount of carbon dioxide produced is decreased 

 in the ratio of 571.35 to 540.58. He records a marked increase in pulse 

 rate after sugar ingestion. In a series of experiments made with coffee 

 he concludes that the taking of coffee decreases both extensively and 

 intensively the respiratory processes. In discussing the pulse rate 

 Bocker states that he does not think there is any necessary connection 

 between the increase or decrease in pulse rate and the increase or 

 decrease in the production of carbon dioxide, nor does he think that 

 the changes in the respiration rate cause a change in the carbon-dioxide 

 production. From a series of experiments on alcohol he concludes 

 that alcohol decreases both intensively and extensively the respiratory 

 processes. 



Smith, 1859. Next to the few classical experiments of Lavoisier and 

 Se"guin no early research is more justly and frequently cited than is that 

 of Edward Smith, who published two papers in 1859. In the first 

 paper 3 he describes in detail his methods of experimentation. A mask 

 with two valves was used, the inspired air passing through a dry gas- 



, Physiologie des menschlichen Athmens, 1892, p. 36. 

 2 B6cker, Beitrage zur Heilkunde, 1849, 1. 

 3 Smith, Phil. Trans., 1859, 149, p. 681. 



