176 THE POPULAR SCIENCE MONTHLY. 



seconds after he has been jumped, we see no sign or indication of what 

 he has just done, or of what he can instantly be made to do. 



On the other hand, the phenomena of trance, of mental hysteria, 

 of the " Jerkers " or " Holy Rollers " may last in any given case from 

 several minutes to several hours or days.* 



Recent German investigations have, by an interesting coincidence, 

 demonstrated that subjects in the mesmeric trance sometimes exhibit 

 the phenomenon of repeating automatically what is said to them. 

 Berger produces this effect by laying his warm hand on the neck of 

 the mesmerized subject, 



2. In the persistence and permanence of the liability to be ex- 

 cited. 



After once the habit of jumping is formed, the subject, though 

 varying in susceptibility at different times, is yet always capable of 

 displaying the phenomena in a greater or less degree at any moment : 

 once a Jumper, always a Jumper, expresses the prognosis. Epidemics 

 of jerking and rolling are, on the contrary, limited in time and in their 

 sphere, disappearing and dying utterly away with the excitements that 

 give rise to them, and the habit of hysteria or of being entranced may 

 also be outgrown. 



Psychologically, these Jumpers, so far as I have been able to see or 

 to learn, are modest, quiet, retiring, deficient in power of self-posses- 

 sion, conceit, and push, but no more so than many others in various 

 races. I had been told that they were of a low order of organization 

 half-breeds, partly French, partly English ; but in this respect I was mis- 

 informed : they are at least as intelligent and as capable of fulfilling the 

 duties belonsxingf to them as the average of their associates who are not 

 Jumpers ; some of them can read and write, and all whom I saw could 

 converse in English with a reasonable degree of intelligence ; possibly 

 as much as we could expect of persons of their age and environment. 

 But all of them, without exception, were of shrinking temperaments. 

 In the chorea epidemics of the middle ages, or of the great religious 

 revivals of this country, this class would be very likely to have been 

 attacked. 



Hereditary. Before I visited Moosehead Lake, while I knew 

 only those facts that were obtained at second or third hand, I felt 

 quite sure that this disease w^ould be likely to be a family inheri- 

 tance. This deductive reasoning was confirmed by inductive observa- 

 tion. It is fully as hereditary as insanity, or epilepsy, or hay-fever, 

 although it has no special relation to any of those forms of disease. 

 In the family of one of those with whom I experimented there were five 

 Jumpers, the father, two sons, and two grandchildren of the respective 

 ages of four and seven years. In the family of another with whom I 

 experimented there were four, all brothers. In the family of another 



* In my work on " Trance " these phenomena are described in more detail than is 

 here possible. 



