64 TRANSACTIONS OF THE 
ses which do not ordinarily function, are, by the con- 
ditions under which mirror-writing takes place, allowed 
to be so.””’ Many subjects were induced to write mirror- 
wise under the following various conditions: Hypnosis, 
Drugs, Abstraction, Insane, Hemiplegia, Feeble-minded, 
Deaf and Dumb, Skilled persons, University students, etc. 
According to his results, the more complete the dissoci- 
ation, whether temporarily induced by hypnosis or by 
drugs, or as a permanent characteristic of the insane, the 
more the subject wrote “mirror-wise.’’ From this he 
concludes that in every case of true mirror-writing “there 
must be a mental disturbance, a dissociation of attention, 
a deflection of the mental content; a low grade of intel- 
ligence or else a serious disturbance of the higher facul- 
ties.”’ 
Fuller’s physiological explanation of reversed writ- 
ing is based upon the fact that any movement of one side 
of the body is accompanied by a potential symmetrical 
impulse of the corresponding part of the opposite side. 
Mirror-writing, he says, is but a specialized instance of 
such associated movements. He goes on: “In every 
instance of stimulation of a nerve on one side of the body 
(primary stimulus), there is, by the arrangement of the 
central paths, opportunity afforded for the stimulation of 
the corresponding nerve on the opposite side of the body 
(secondary stimulus). It will thus occur that the graphic 
representation of the secondary stimulus will be an exact 
mirror replica of the graphic appearance of the primary 
stimulus. Accordingly, all symmetrical movements may be 
traced ultimately to a single brain area. From this area, 
the motor complex of the side primarily intended to be 
active receives its stimulus. The opposite side is stimu- 
lated to a lesser degree either by its direct connection 
with the primary area; or indirectly by its connection 
with the opposite motor complex; probably both means 
are available. For the purpose of mirror-writing it is 
most convenient to assume the truth of the second alter- 
native, viz., that the connection is with the opposite motor 
cortices through the corpus collosum.” 
Fuller concludes then that “upon the use of the right 
hand for ordinary writing depends our ability to write 
mirror-wise with the left hand. It is a necessary condi- 
