1913] N- R- Blatherwick and P. B. Hawk 31 



use of the larger tubes shortens the time of the Sedimentation, at the 

 same time making as good a Separation as is procured by the use of 

 the smaller tubes. Another point of difference was the manner of 

 transferring the bacterial substance to the Kjeldahl flasks after the 

 final Sedimentation. It was found, after some experimentation, 

 that the bacterial substance settled more completely to the bottom of 

 the centrifuge tube when the bacteria were suspended in sulphuric 

 ether instead of ethyl alcohol. In all these analyses the sediment 

 from the alcohol was therefore centrifuged with ether, the sediment 

 being transferred to the Kjeldahl flask and the nitrogen determined 

 in the usual way. 



The centrifuge used in this experiment was run by an electric 

 motor, which developed a speed of 1,400 revolutions per minute. 

 It will be noted here that this is a slower rate of speed than is gener- 

 ally used. More will be said of this in a later connection. 



SuBjECTS, PLAN, DiET, ETC. Two studcuts, normal in every 

 respect, were given a uniform diet for several days or until nitro- 

 gen equilibrium was reached, as shown by analyses of foods and 

 excreta. During this period (preliminary), 100 c.c. of distilled 

 water were taken with each meal. Besides this, 200 c.c. of distilled 

 water were ingested by subject V at 10 A. M., at 3 P. M., and at 

 8.30 P. M. Subject C ingested a total of 400 c.c. at these hours. 

 After the subjects had reached nitrogen equilibrium, they were 

 placed on the " moderate water " diet, which differed from the pre- 

 liminary only by the addition of 500 c.c. of distilled water at each 

 meal. This made for subject V a total water-ingestion of 900 

 c.c. during the preliminary period, and of 2,400 c.c. during the 

 "moderate water" period. The values for subject C were 700 

 c.c. and 2,200 c.c. respectively. The duration of the "moderate 

 water" period was ten days. The subjects were then returned 

 for an interval of five days to the diet of the preliminary period, this 

 period being called the intermediate period. The " copious water " 

 period was then begun, and continued five days. The diet during 

 this period differed from that of the preliminary and intermediate 

 periods by the addition of 850 c.c. of distilled water at each of the 

 three meals, making a total daily ingestion of 3,450 c.c. for sub- 

 ject V, and of 3,250 c.c. for subject C. The diet of the preliminary 



