15 



good company, and, in general, an agreeable environment tend to pro- 

 mote the favorable progress of digestion. A reversal of the conditions 

 of environment to the disagreeable, combined with mental depression, 

 bad news, and other unfavorable conditions, have exactly the opposite 

 effect. 



The question, therefore, arose in connection with the experimental 

 work as to the advisability and possibility of preventing the mental 

 attitude from producing any effect. A careful consideration of all the 

 conditions of the problem made it clear that it would be impossible to 

 conduct the experiments in any way which would exclude from the 

 knowledge of the participant the fact that preservatives were added to 

 the food. It was fully understood that he was employed for this pur- 

 pose, and the very moment that the observation began upon his daily 

 life, by weighing the food and collecting the excreta, he would be 

 aware of the fact that he was under observation and was probably par- 

 taking of preservatives. 



The question also arose whether or not the preservatives should be 

 given in capsules openly or whether they should be concealed in the 

 food itself. Both of these methods received a thorough experimental 

 trial. When the preservative was mixed with the food in such a way 

 as to conceal its physical appearance, a certain dislike of the food in 

 which it was supposed to be was manifested by some of the members 

 of the table. Those who thought the preservative was concealed in the 

 butter were disposed to find the butter unpalatable, and the same was 

 true with those who thought it might be in the milk or the coffee. 

 When, on the other hand, the preservative was given in the capsules 

 with the full knowledge of the subject, much less disturbance was 

 created. In fact, after a day or two, when the subject became used to 

 the fact that he was taking a preservative, it was apparent that the 

 effect of the mental attitude was not at all noticeable. All the foods 

 offered were relished because they were known to contain no preserva- 

 tive, while the preservative, itself, exhibited in the form of a capsule, 

 imparted no bad taste or other disagreeable effect. 



If an experiment of this kind were to be continued only a few days it 

 is evident that the mental attitude of the subject would be a matter of 

 much concern, but when from 30 to 70 days are employed in one series 

 of observations, and especially when the observations are continued for 

 many months, this effect rapidly wears away, and probably does not 

 influence the final results in any appreciable manner. 



The young men were cautioned to avoid discussing the development 

 of any symptoms which they might notice among themselves and were 

 urged not to dwell upon any indications of abnormal conditions which 

 they might experience, but to keep their minds employed on their usual 

 vocations and to avoid thinking, as much as possible, about the experi- 

 ts which they were undergoing. In most cases this course of pro- 



