326 
to be concerned with the sensations of 
touch, pain and temperature. Regarding 
the localization of mental states in these 
other areas, we have other suppositions 
which are to be believed as much as that 
regarding the mental functions of the post- 
central area. One of these, that the layers 
of the cortex in the so-called visuo-sensory 
sphere function to produce sensations of 
different color is a more bizarre supposi- 
tion, and has even less clinical evidence in 
its support. 
Many neurologists and some psycholo- 
gists appear to believe that we have data 
which enable us to locate certain definite 
mental processes in parts of the cerebral 
cortex outside of the motor and sensory 
spheres. The disorders of speech, of the 
nature of aphasia, which are considered by 
some to be mental abnormalities, are due 
to localized injuries or destructions of 
parts of the brain. That the third frontal 
convolution, the area to which Broca as- 
signed the function of motor speech, has a 
different structure than the surrounding 
regions, as has been contended by Brod- 
mann, is a point made in favor of the local- 
ization of the speech function in this area. 
The criticisms of von Monakow and of 
Marie are, however, too trenchant to be 
disregarded, and the negative cases which 
they have cited are sufficient evidence that 
neither the mental processes connected with 
motor speech nor the supposed cortical 
speech mechanisms are definitely located in 
the part of the brain to which they were 
assigned by Broca, by Wernicke and by 
their followers. 
One of the histologists has written: ‘‘It 
is unfortunate that we can not say that 
word deafness is invariably due to a lesion 
of the left superior temporal gyrus. Au- 
thentic cases have been recorded in which 
there has been no affection of this convolu- 
tion and these, of course, increase our diffi- 
SCIENCE 
[N.S. Vou. XXXV. No. 896 
culty in interpreting the condition.’’ In 
another place he admits that the localiza- 
tion of this condition, even as a clinical 
phenomenon, rests upon only two cases 
which have been checked by careful post- 
mortem examination. Disregarding the 
number of cases which may properly be 
cited in support of the localization of this 
part of the speech function in this part of 
the cortex, it should be remembered that 
even one negative case is sufficient to 
demolish the whole structure of the mental 
speech function localization. 
On the basis of the histological studies, 
we have also another kind of phrenological 
localization. This is a localization of par- 
ticular processes of a mental order in cer- 
tain layers of cells in the cortex. It will 
be remembered that the cortex is composed 
of rather distinct layers of cells with their 
fibers. Some histologists believe there are 
six layers, others five. Some of these layers 
have been disregarded in the formulation 
of the speculations. Bolton and Ariens 
Kappers believe that the layers have re- 
ceptive and associative functions. Bolton 
disregards the first and fourth layers (he 
counts only five instead of six, as does 
Brodmann) and postulates the following 
functions for the other three layers: for the 
outer pyramidal layer he assumes a “‘psy- 
chie or associative function,’’ for the third 
layer a receptive function, and for the fifth 
layer the function of lower voluntary and 
instinctive activity. 
These facts indicate the general trend of 
the histological localization of function, 
and its tendency toward phrenology. 
What shall we say against this view or 
what shall be our attitude towards it? 
Brodmann assumes that the principle of 
localization has been settled, and all that 
needs to be done at present is to consider 
the ‘‘how’’ and ‘‘what’’ of localization. 
This view can not, however, be accepted. 
