64 Miss H. Chick and Miss E. M. Hume. The Effect of 



Wheat embryo, in which the anti-beri-beri experiment is highly con- 

 centrated, was selected as suitable material for the present experiments, and 

 50-100 grm. were heated in a steam autoclave at different temperatures for 

 different intervals of time. It was found that the interior of the material 

 very slowly acquired the temperature of its surroundings, and special steps 

 were taken to ascertain the exact temperatures experienced. In cases where 

 the material was steamed at 100° 0. (Expts. 2 and 3, Table I) the real internal 

 temperature was measured by means of a maximum thermometer, whose bulb 

 was inserted in the middle of the mass to be heated, and whose stem 

 projected through the neck of the bottle containing it. The whole was lifted 

 from the steamer for an instant at intervals of about 20 minutes, in order to 

 obtain readings from the thermometer and to construct a curve of rise of 

 temperature. In case of temperatures above 100° C. this procedure is not 

 possible, and it was necessary to make special control experiments in which 

 similar amounts of similar material were placed imder exactly the same 

 conditions as those of the actual test. Steam was blown off after various 

 intervals of time from the start, the autoclave opened and note taken of the 

 maximum temperatures registered both inside the vessel containing the 

 wheat germ, and outside in the autoclave. By means of a series of such 

 tests made separately, a temperature curve was constructed from which an 

 accurate estimate could be made of the temperatures actually experienced by 

 the material exposed. The data upon these points are set forth in the first 

 three columns of Table I, above. 



The experiments fall into two classes (o) those at or near 100° C, devised 

 to be applicable to the ordinary processes of cooking, and (5) those above 

 100° C, intended to give information as to what may be expected to happen 

 during sterilisation of tinned and canned foods. The effect on the properties 

 of the wheat germ of exposure to these temperatures was studied by the 

 following method. Comparison was made of the minimum doses of 

 {(t) original and (b) heated germ required to cure pigeons (of weight 

 300-400 grm.) acutely ill with polyneuritis, brought on by an exclusive diet 

 of polished rice. From the results given in Table I it is seen that destruction 

 of the anti-neuritic vitamine progresses very slowly at 100° C. or thereabouts. 

 In fact, after two hours' exposure to such a temperature (Expt. 3) our 

 experiments fail to reveal any significant loss in anti-neuritic properties — 

 the curative dose of the heated " germ " remaining about 2-5 grm., the same 

 as that of the unheated material (Expt. 1). After exposure for 40 minutes 

 to a mean temperature of about 113° C. the efficiency, compared with the 

 unheated control, is reduced to about one-half, and after subjection to 

 118°-124° C. for two hours, to something less than a quarter, possibly to 



