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Francis Darwin. 
It is for this reason that even in plant physiology we want the idea 
of a individuality, a something on which the past experience of the 
race is written and in which the influences of the external world 
are weighed. I do not of course imply conscious weighing, nor 
do I mean that the plant has memory in the sense that we have 
memory. But a plant has memory in Hcring’s and S.Butler’s sense 
of the word, according to which memory and inheritance are 
different aspects of the same quality of living things. Thus in 
the movements of plants, as in the instincts of animals, the 
spontaneity of the individual has disappeared, the balance of profit 
and loss has been struck during the past experience of the species, 
and the individual acts by that unconscious memory we call 
inheritance. 
My view of the nature of stimulus and reply depends on what 
in mental processes is known as association. The smell of a flower 
or the recurrence of a bar of music may act on a man as a stimulus 
in virtue of their association with events in his past life. I want to 
be able to talk about association without connoting mental processes 
and I shall therefore devote a short time to a remarkable book “ Die 
Mneme ” by R. Semon, in which a terminology has been framed, 
which is equally applicable to the movements of a plant or the 
thoughts of a man. 
Semon contrasts the behaviour of a puppy who takes no notice 
of a boy stooping to pick up a stone with that of an adult dog 
(experienced in the ways of boys) who runs when he sees the stone 
picked up. 
When the puppy has for the first time been hit by a stone, he 
receives two stimuli, viz : the image of the boy on his retina and the 
pain from the blow of the stone. The result is that the organism 
is permanently changed ; before, the stone-throwing produced no 
perceptible effect, while the pain caused him to run. Afterwards 
the effect of running away can be produced by the retinal stimulus. 
The permanent change in the organism he calls an digram or 
record, something written or engraved on the organism. Thus the 
image of the boy gives the engram I. the pain of engram P. Two 
engrams occurring together (or in close succession) tend to be tied 
together. Thus when the dog again sees a stooping boy the 
engram 1. is called up and brings with it P., to which it is united. 
In this case the result (the running away) is ecphorically produced, 
which I imagine to mean a dragging out or revival of one engram by 
another. The whole process he calls mnemic—not that it implies 
