VITAMIN G (B,) 133 



equal numbers and follow the general technique of Chick and Ros- 

 coe (1928). 



In the method developed by Bourqidn (1929) from the Sherman- 

 Spohn (1923) method described in Chapter II vitamin B (BJ is sup- 

 plied, as suggested by the work of Sandels, by incorporating into the 

 basal diet an alcoholic extract of ground whole wheat. This extract is 

 prepared as follows : 



Eight hundred grams of freshly ground wheat is shaken with 1.5 

 liters of 80 per cent alcohol by weight, for an hour and a half. The 

 extract is then filtered through a Biichner filter with suction. The 

 residue is again treated with a liter of 80 per cent alcohol, shaken for 

 an hour, filtered and the residue washed with 300 cubic centimeters of 

 the alcohol. The combined extracts are concentrated in vacuo for an 

 hour to an hour and a half or until about one-fourth the original 

 volume, poured upon 300 grams of cornstarch and dried under an elec- 

 tric fan at room temperature. In the preparation of the alcohol allow- 

 ance is made for the water content of the wheat (average about 10 

 per cent). 



Her modification of the Sherman-Spohn diet has the following 

 composition: purified casein, 18 per cent; Osborne-Mendel salt mix- 

 ture, 4 per cent ; butterfat, 8 per cent ; cod-liver oil, 2 per cent ; corn- 

 starch, 68 per cent, a part of which carries the alcoholic extract from 

 50 grams of whole wheat for each 100 grams of diet. 



For use in these experiments are recommended young normally 

 growing animals (rats) 28 to 29 days old, reared by mothers on a diet 

 consisting of two-thirds finely ground whole wheat, one-third whole milk 

 powder, and sodium chloride to the extent of 2 per cent of the wheat 

 with a daily addition of about 5 grams of fresh lean beef per adult. 

 They are confined in cages with raised screen bottoms and fed the 

 basal diet alone until they cease to grow (14 to 18 days), at which time 

 the test period proper is begun. For quantitative comparative studies 

 all the precautions necessary to insure accuracy as discussed in con- 

 nection with vitamin A and vitamin B determinations should be 

 observed. 



Animals receiving the basal diet alone, "negative controls," almost 

 invariably live throughout an 8-week experimental period, losing weight 

 very slowly but steadily. The work of several independent investigators 

 in our laboratory shows that under the conditions briefly outlined here 

 the gain in weight over the negative controls is proportional to the 

 allowance of vitamin G within those amounts permitting from 2 to 5 

 grams gain per week for an 8-week period, when natural food materials 



