496 F. H. PIKE 
response by one preceding it, and when we consider also the 
considerable number of afferent impulses which may be in- 
volved in such a reflex response as the maintenance of an atti- 
tude of the body or a part of it, or in the maintenance of equi- 
librium, the actions become bewildering in their complexity. 
The study of the specific reflex response to stimulation of a 
given afferent nerve and of the modifications of any given re- 
sponse which occur when any particular component of the affer- 
ent group is lacking are of importance not only from the point 
of view of the physiologist, but from the point of view of the 
clinician as well. One aid in diagnosis which the clinician 
employs is the study of the modification of typical’ motor re- 
sponses which occurs when any particular afferent channel or 
channels are blocked. Considerably more precision of facts 
and ideas is necessary before this particular aid attains to its 
maximum usefulness to the clinician. 
Other writers have also recognized this dependence of the 
normal response upon afferent impulses from various sources. 
Upon some such basis, if I get its significance correctly, must the 
idea of the integrative action,—a summing up of afferent im- 
pulses within the central system—of the nervous system be 
founded. I have expressed elsewhere the belief that the idea of 
the integrative action of the nervous system is one of the great 
principles of the physiology of the nervous system. It under- 
lies all the work of Pawloff on conditioned reflexes. And all 
the work of Pawloff goes to show that it is in the cerebrum that 
the summing up of the afferent impulses so necessary for the 
finer sensory discriminations occurs. Instead of being an 
argument against cerebral localization, as I have once or twice 
seen intimated, it seems to me that Pawloff’s work is an argu- 
ment in favor of localization. The description in physiological 
terms of any response occurring through the nervous system 
must include an account of all the afferent impulses which enter 
into its inception and control, the central mechanism of this 
integration, and the efferent pathway. The relationships of the 
various afferent impulses concerned are not always obvious 
from the anatomical relations. Most of the instances in which 
