1884.] Moral Epidemics and Contagions. 571 
brain to brain without losing its nature may be followed, 
thanks to the means which Science puts at our disposal, 
step by step, from its point of departure to its point of 
arrival, without being lost to sight for a moment or es- 
caping from our observation. There is here nothing Jhypo- 
thetical. 
This propagation of the identity of the cerebral movement 
has not been contested by any of the savants who have fol- 
lowed M. Rambosson’s demonstration. It appears that this 
movement produces different phenomena in different media, 
but without changing its nature, — i. e., it reproduces identical 
or analogous phenomena whenever it encounters an identi- 
cal or analogous medium. 
In this law of the transmission and transformation of the 
movement which produces the contagion there are two prin- 
cipal points to be considered : — 
1. The cerebral movement which passes from brain to 
brain without changing its nature. 
2. The reflex aCtion which this movement tends to deter- 
mine after reaching the brain, and which becomes 
the proximate cause of the contagion. 
The reflex aCtion which this movement tends to determine, 
and which realises the contagions in question, does not 
always take place, and this faCt has raised some objections 
on the part of those who are not perfectly familiar with the 
nature of reflex aCtion in its different phases. But these 
objections do not affeCt the law, which is indeed confirmed 
by their scientific explanation. 
The contagion of nervous phenomena ensues, then, as the 
immediate consequence of a reflex movement. 
All that is observed in the production of an ordinary reflex 
movement is equally observed in the propagation or conta- 
gion of these phenomena. There is an essential difference 
in the origin of the physiological movement which produces 
ordinary reflex aCtion and that of the physiological move- 
ment which produces the contagion. 
The first-mentioned has its origin in the same person in 
whom the reflex phenomenon is manifested ; whilst the other, 
producing the contagion or the propagation of the pheno- 
menon to a distance, has its origin in a strange brain (a very 
strange one, sometimes, in a quite different sense of the 
term !), and is transmitted through the ambient medium to 
the brain of the person whom it attacks. 
For instance, digestive troubles or hindrance in respiration 
give rise to a centripetal movement which on arriving at the 
2 P 2 
