PLAN OF THE INVESTIGATION. 19 



accidental environmental effects, such as those produced by changes of 

 temperature, light, humidity, etc. Except in a few isolated cases we 

 have no knowledge at all of the mental consequences of such complex 

 vital processes as are involved in the secretions of the various ductless 

 glands, changes in blood-pressure and pulse-rate, the ingestion of 

 different foods, and various kinds of muscular activity. 



As far as these various factors were known to influence the question 

 at issue, they were more or less completely avoided by the arrangement 

 of our experimental program. For example, we endeavored to avoid 

 the interplay of possible weekly, as well as daily, rhythms by experi- 

 menting on each subject, in so far as possible, only once a week on the 

 same day of the week, at the same time of day, and at the same time 

 after eating. (The group of psychopathic subjects made the only 

 exception to this rule. They served as subjects five consecutive days.) 

 But the climatic changes were not controllable. Moreover, from the 

 data that we regularly collected at the beginning of each experimental 

 session, it is clear that in the comparatively even life of students 

 there were more or less conspicuous differences in the conditions which 

 immediately preceded our experiments. The weekly routine of work 

 and relaxation was far from constant. Neither the amount nor the 

 kind of food could be accurately predetermined. Slight indispositions, 

 differences of subjective tiredness and sleepiness, and probable differ- 

 ences of real fatigue developed as the experimental sessions progressed. 

 To have interrupted or deferred the experiments whenever any of these 

 differences appeared would have lost much time and have enormously 

 increased the number of experimental periods. To have demanded 

 rigid controls and strict regulation of life would have meant the loss of 

 all our subjects of the student class, and possible serious mental dis- 

 turbances in the others. The complete elimination of physiological 

 variation would be utterly impossible in human beings. 



For the purpose of our experimental investigation we were conse- 

 quently forced to regard all the rhythmic and arrhythmic variables 

 which we could not eliminate as accidents which a sufficiently large 

 number of instances should tend to distribute, without bias to the 

 question at issue. While we must carefully protect the experiments 

 from every known bias, we must realize the possibility that in any 

 given instance the real effects of alcohol may be completely masked by 

 the accidental variables, and on the other hand, that on occasion the 

 real effects may be more or less grossly exaggerated. Within the 

 physiological limits which are prescribed by our immediate problem, 

 viz., the effects of moderate doses, we can not expect any fundament- 

 ally important neuro-muscular process to entirely disappear. Neither 

 may we properly expect the appearance of a new specific reaction to 

 alcohol within the limits of our selected measurements. All that we 

 can legitimately expect to say at the end of our investigation is that 



