DEDIFFERENTIATION IN PEROPHORA 683 
the nervous system is based on a struggle for expression between 
many potentially-different activities ’. Integration of function, 
however, is not all. A number of integrated minor systems 
may exist, one in actuality, the rest in potentiality, m the 
developed human psycho-neural system as a whole ; and there 
is also a form of struggle between them. The particular type 
of mental disorder known as regression is only one special 
case of the results of differential susceptibility among two or 
more such minor systems. In other so-called neurasthenic 
eases the second, normally-suppressed system may not be a 
system of childish memories, but an imaginary ‘ ideal’ world 
of thought along whose paths consciousness flows instead of 
along those necessary to maintain adaptation to everyday 
life; or else it may be the system of ‘ negative’ emotions, 
leading to depression and possibly to suicidal attempts. 
Dissociation of personality and subsequent alternation of the 
sub-personalities may also, though less directly, be included 
under the same rubric. Rivers, in a recent work (1920), has 
emphasized the same point of view ; he points out for psycho- 
logical systems what I have drawn attention to in this paper 
for physical systems—that reversal of dominance in a balanced 
system may occur either through the action of unfavourable 
agencies on the dominant system (differential inhibition) or 
of favourable agencies on the subordinate system (differential 
stimulation). 
In a case of regression mentioned by Dr. W. MacDougall and 
Dr. Hadfield in their lectures and confirmed to me in conversa- 
tion by Lt.-Col. Good, of Ashhurst Hospital, a young man 
actually regressed to the condition of an infant.1 He was 
unable to talk or walk, and could tolerate no food except milk. 
(By some freak of the nervous mechanism two associations 
and two only remained from adult life: if a cigarette were 
offered him he would light and smoke it ; when shown a horse 
or a picture of a horse, he would get astride of some object 
and ‘tchk’ as if encouraging a horse. It turned out that he 
1 Since the above was written, I find that an account of this and 
similar cases has been published by MacDougall in ‘Journ, Abn. Psych,’ 
15, 1920, p, 136. 
