16 



cedure had its desired effect, and from the general deportment of those 

 upon whom the experiments were made it may be stated, with a con- 

 siderable 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 subjected 

 probably produces a mental attitude more prejudicial to normal physio- 

 logical processes than that produced in the case of the man who under- 

 stands 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 conclu- 

 sions 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 by the great 

 majority of our people that added preservatives are always injurious and 

 in many instances poisonous. But even when personal bias, weight of 

 authority, and public opinion are eliminated from the problem, it is 

 still a most difficult one. So many elements enter into its study, so 

 many conditions difficult to control, so many idiosyncrasies are to bl 

 reckoned with, so many external causes influencing health are beyond 

 control, that it is difficult in many cases to decide, where variations are 

 noticed, as to the exact or even the apparent cause which has produced 

 them. 



The problem, therefore, has been attacked with a full knowledge of 

 its difficulty and with the desire to be conservative and free from dog- 

 matism. It would probably be better if all the detailed data which 

 have been secured could be printed in connection with this discussion, 

 so that the critical reader might be able in every instance to refer to 

 the original figures. Enormous space, however, would be occupied b; 

 the data, and the fact that in most cases they would be of little use i 

 detail has led to the decision to publish only summaries, with such 

 detail as may be necessary to point out the way in which the general 

 data have been obtained. If, as may appear later on, all points of th 

 problem have not been elucidated, the failure has not arisen either fro 

 lack of .desire or from want of industry in the conduct of the experiment. 

 It is to be attributed rather to the limitations placed upon the observers, 

 either by lack of experience or by lack of knowledge how to properly 

 classify, digest, and study the data at their disposition. A serious 

 attempt has been made to present these data in their full significance, 



