30 INFLUENCE OF FOOD PRESERVATIVES ON HEALTH. 



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 unpala- 

 table, 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 preservative, while the preservative itself, 

 exhibited in the form of a capsule, imparted no bad taste or other dis- 

 agreeable 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 thirty to seventy days are employed in 

 one series of observations, and especially when the observations are con- 

 tinued 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 among themselves 

 any symptoms which they might notice, and 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 experiments which they were 

 undergoing. In most cases this course of procedure had its desired 

 effect, and from the general deportment of those upon whom the 

 experiments were made it may be stated, with a considerable degree 

 of confidence, that the mental state as a whole had very little influence 

 upon the course and progress of digestion. 



It is in this particular, namely, the mental attitude, that experiments 

 conducted with artificial digestion and experiments conducted upon 

 the lower animals have decided advantages. Yet it must be admitted 

 that in the latter case the confinement to which the animals are sub- 

 jected probably produces a mental attitude more prejudicial to normal 

 physiological processes than that produced in the case of the man who 

 understands fully the conditions which surround him. 



CLASSIFICATION AND INTERPRETATION OF THE DATA. 



The great difficulties of correctly studying the extensive data which 

 these experiments have given and drawing therefrom the proper 

 conclusions are fully realized. The utmost care must be exercised in 

 these cases to remove all possible personal bias and to free oneself, in 

 so far as possible, from the weight of authorities which have been 

 consulted. Public opinion also must not be forgotten in this respect, 

 especially when it is considered that it is almost universally believed 



