14 



That such errors have been wholly excluded from the data submitted is 

 not likely. On the other hand, errors of this kind which may have been 

 introduced could not have been purposely made in order to modify the 

 final results of the investigation. Hence it is fair to assume that such 

 errors are to a certain extent compensatory, and that they do not affect 

 seriously the conclusions based upon the data as a whole. Those who 

 have worked in investigations of this kind, however, will understand I 

 the great difficulties which attend them, as well as the care which has i 

 to be exercised in their conduct, and will be the more ready to excuse 

 any unavoidable error which may have crept in, either in the conduct of 

 the work or the morale of those who were subjected to the experiment. 



EFFECTS OF REGULAR HABITS OF LIFE. 



Another important factor must be considered in the interpretation of;! 

 the data which have been obtained in these experiments, namely, the 

 effect of regular habits of living, uniform quantity of diet, and general 

 control of the appetite upon the physical well being of the subject. 



It is usually considered by physiologists and physicians that regular 

 habits of life conduce to health and strength. This theory has been 

 corroborated by the results of the experimental work here detailed. 

 While it is true that in -many instances during the progress of the 

 investigation the members of the table were made temporarily ill by 

 the quantities of the preservatives administered, it is, nevertheless, anj 

 interesting fact to note that at the end of the year after the final " after 

 period" had been passed, they appeared to be, and declared themselves 

 to be, in better physical condition than when they entered upon the 

 experimental work seven months before. 



This fact, as has already been stated, must not be neglected, since it, 

 is evident that the tendency toward a good physical state and good 

 health produced by the regular habits of life might counteract the 

 unfavorable tendency of any exhibited preservative, so that at the end 

 of the observation, if the results were judged only by the condition of 

 the subject at that time, they might be pronounced negative or even 

 helpful, whereas in point of fact, the preservative might have produced 

 injurious effects. Self-restraint, temperance, regularity of exercise, reg- 

 ularity in hours of sleep and hours of work are believed to have favora- 

 ble effects, and these were manifested in a marked degree throughout 

 the whole of the experimental work. 



MENTAL ATTITUDE. 



That the personal attitude of the individual experimented upon 

 influences, to a certain degree, the progress of digestion is undoubtedly 

 true. Every physician and physiologist is familiar with the marked 

 effect which mental states produce upon the bodily functions. These 

 effects may be either favorable or unfavorable. Cheerful surroundings, 



