BawpkEn, Psychological Theory of Evolution. 259 
sciousness has been ascribed even to the spinal cord because 
many of its functions are purposeful. But, as Professor LoEB 
has pointed out, there is evidence of purposeful response even 
in the tropisms of plants and, in his opinion, we are equally 
warranted on this principle in ascribing consciousness to ma- 
chines and even to molecules and atoms. Evidently this cri- 
terion does not help us forward any, since it is no anwer to the 
question as to the limits of consciousness to reply that all proc- 
esses are conscious, including the chemical and physical rela- 
tions of atoms and molecules. This at best simply shifts the 
problem back a step, since if all natural processes are conscious 
we still have to ask what are the limits of that peculiar form of 
consciousness which marks off the rational from the instinctive 
act. If by purposiveness is meant evident adaptation of means 
to ends, then purposiveness cannot be an adequate criterion for 
the presence of consciousness, since we find evidence of such 
adaptation throughout nature, as well in the inorganic and un- 
conscious as in the organic and conscious sphere. Attention 
is called to this principle as a criterion of consciousness because 
it is a good illustration of the uncritical popular attitude toward 
the problem, which has found its way even into such works as 
that of ALFRED BINET in his study of ‘‘The Psychic Life of 
Micro-organisms,’’ where the criterion used is choice or power 
on the part of an organism to discriminate and make a selection. 
A more critical and scientific attempt to determine the 
criterion of consciousness is found in Professor Lors’s doctrine 
of ‘‘associative memory.’’ By ‘‘associative memory” he means 
‘that mechanism by which a stimulus brings about not only 
the effects which its nature and the specific structure of the 
irritable organ call for, but by which it brings about also the 
effects of other stimuli-which formerly acted upon the organism 
almost or quite simultaneously with the stimulus in question.” 
Consciousness goes out with ‘‘associative memory”’ in sleep, in 
anaesthesia, in the faint, in coma due tc poisons, etc. Hence 
‘‘associative memory” is essential to consciousness. Conscious 
1 Comparative Brain Physiology and Comparative Psychology (1900), p. 12. 
