DEVELOPMENT — DEVELOPMENTAL INSANITIES 
to adaptation, growth to Accommodation 
(q. v.). In addition to the topics referred to, 
see Embryology. 
Literature : see topics mentioned above ; 
Hyatt, Science, N.S., Jan. 27, 1897 ; 
HAECKEL,Gen.Morphol.(i866). (j.m.b.,e.b.p.) 
Development (mental) : see Mental De¬ 
velopment, and Evolution (mental). 
Development Formula : see Symbolic 
Logic. 
Developmental Insanities: Ger. Entwick¬ 
lungspsychosen ; Fr. psychoses du développe¬ 
ment ; Ital. psicosi dello sviluppo (e.g. della 
puhertà). Those nervous disorders which tend 
to appear at certain periods in the growth and 
development of the brain. 
The bringing to complete fruitage of the 
highest evolution in nature is a most delicate 
process, subject to dangers of many kinds, and 
incident to different periods. "While these may 
be aggravated by unhygienic conditions, the 
determining factor is heredity. ‘ A bad or a 
good heredity means more during development 
than after/ Most of the disorders of develop¬ 
ment are accordingly regarded as manifesta¬ 
tions of nervous instability, or of a neurotic dia¬ 
thesis. Such taint may be so slight that, under 
ordinary circumstances, the individual would 
pass through his normal span of years without 
mental disorder or marked abnormality ; 
but under the influence of misfortune or ex¬ 
citement, particularly if it occur at critical 
periods in his life, he is apt to exhibit patho¬ 
logical symptoms. Those bearing upon them 
the marks or stigmata of Degeneration (q. v.) 
are specially prone to developmental neuroses. 
Developmental disorders in children are 
apt to take the form of convulsions, delirium, 
night-terrors, somnambulism, and the like. 
During dentition, convulsion is the typical 
form of manifestation of an unstable brain. 
The delirium may be connected with a distinct 
fever, but the high temperature does not of 
itself lead to delirium except in the predis¬ 
posed brain. 
The developmental neuroses incident to 
puberty and adolescence are of supreme im¬ 
portance ; for these periods are recognized as 
the ones when breakdown is most imminent, 
when the tyranny of heredity is most apt 
to make itself felt, when the decadence of 
the unfit begins to appear. Epilepsy and, 
especially, hysteria are apt to appear in the 
years following puberty. 
The ages from twenty to twenty-five are 
most liable to mania and neurasthenia ; and 
the percentage of cases of insanity which occur 
at this period, in which hereditary influences 
can be traced, is unusually large. Many of the 
forms of mental disturbance incident to this 
period, while not technically insanities, are yet 
significant. A characteristic form of minor 
psychosis may appear as an exaggerated self- 
will : the youth or maiden becomes ungovern¬ 
able, breaks out into attacks of violence, 
becomes lazy, may be prone to deceit and lying, 
may leave home without reason, or create 
scandal. In all this there is a characteristic 
periodicity, periods of abandonment and ex¬ 
cess giving way to periods of propriety and 
self-restraint. It would be misleading to re¬ 
gard such attacks as insanity, but they are 
closely related causally to the influences which 
produce true insanity. The form of insanity 
usually described as the insanity of adolescence 
is characterized by a maniacal tendency 
(seventy-eight per cent.) and a motor restless¬ 
ness. ‘ The maniac is, in the male sex, restless, 
boisterous, full of mock-heroic pseudo-manli¬ 
ness, obtrusive pugnaciousness, with often a 
morbid sentimentality ; while in the female 
sex we find also restlessness, with lack of 
self-control, intolerance of control by others, 
impulsiveness, hysterical obtrusiveness, and 
emotional perversion. In both sexes we 
naturally find strong and perverted sexual 
ideas and practices/ Periodicity of attack and 
remission is particularly characteristic, and is 
related, in women especially, to the periodicity 
of sexual functions. In about one-third of all 
cases the ending is secondary dementia—a 
severe decay of mental functions, comparable 
to extreme idiocy. Such dementia, however, 
may be consistent in some cases with the 
spasmodic, but transitory, display of latent 
mental powers. Some cases recover once or 
twice with years of sanity, but in the end pass 
into true dementia. Less frequently the 
adolescent insanity is of a melancholic type, 
still showing remissions, but not so definitely 
as in maniacal cases ; there is apt to be 
hypochondria and extreme concentration upon 
one’s self. Suicidal tendencies may occur; 
religious depression and delusions are frequent. 
Such cases when persistent developinto forms of 
stupor—more common in females than in males. 
Masturbation in males, and hysterical symp¬ 
toms in females, are the chief complications. 
Akin to adolescent insanities are those con¬ 
nected with childbirth, with the climacteric, 
and with senility. All these relate to periods 
of development in the progress from birth to 
death, and are dominated by hereditary in¬ 
fluences and endowments. For description of 
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