ETIOLOGY OK BERIBERI. 295 



polishings employed at first mixed with the rice and also for the 

 purpose of making the alcoholic extract that was used through- 

 out the experiment were also especially prepared by this firm 

 and were free from grain weevils. The commercial polishings 

 for sale in the markets always contain weevils in great abund- 

 ance, and it is very difficult or impossible to separate them 

 from the polishings. 



PREPARATION OF THE EXTRACT OF RICE POLISHINGS EMPLOYED. 



The extract of the polishings was prepared by Mr. Hocson 

 of the physiological laboratory of the College of Medicine and 

 Surgery to whom we wish to express our thanks. The extract 

 was always freshly prepared every third day and used before 

 any deterioration could have occurred. The method of prepara- 

 tion employed, which was essentially that of Chamberlain and 

 Vedder,'^ was as follows: 



Five kilograms of rice polishings (dardc) were extracted with 14,000 

 cubic centimeters of 95-per-cent alcohol by three successive macerations of 

 twenty-four hours each, using for the first day 6,000 cubic centimeters and 

 for the second and third 4,000 cubic centimeters respectively. After each 

 day of maceration the liquid was strained, pressed, filtered, and the filtrate 

 transferred to a porcelain dish to facilitate the evaporation of the alcohol 

 of which there was a large amount present, a portion of the alcohol was 

 evaporated more rapidly by means of an electric fan and the fat separated 

 from the extract. The extract was then concentrated to 125 cubic centi- 

 meters in vacuum at 60 °C., and the residue obtained was made up in volume 

 to 625 cubic centimeters with distilled water and filtered. 



EXPERIMENT. 



We shall now proceed to consider the experiments in detail. 

 The nature of the rice received by each individual is stated at 

 the beginning of the summary of his history during the ex- 

 periment. In general, it may be mentioned that the groups were 

 fed for the greater part of the time occupied by the experiments 

 as follows : 



Group L White rice + extract of rice polishings + special diet. 

 Group II. White rice + special diet. 

 Group III. Red rice -|- special diet. 

 Group IV. White rice + special diet. 



For about the first thirteen days Group I were fed white rice 

 mixed with the rice polishings, as we had not sufficient extract 

 on hand to begin the experiment with this group; and Group III 

 for the first seventeen days were fed white rice mixed with 



" This Journal, Sec. B (1911), 6, 254; (1912), 7, 40. 



