52 VITAL FORCE, INSTINCT, AND SENSATION. 
moist earth, the protoplasm in the majority of cases begins to bestir itself and 
to move, and the embryo grows out into a seedling. After twenty years, perhaps, 
only about five per cent of the seeds preserved would germinate. The rest are not 
stimulated by damp earth to further development; their protoplasm no longer 
possesses the power of augmenting its volume by absorption of matter from the 
environment, or of developing a definite form, but is disintegrated by the influx of 
air and water and breaks up into simpler compounds. After thirty years hardly 
one of the seeds would sprout. Yet all these seeds were kept throughout the time 
at one place and under precisely the same external conditions; nor can the slightest 
change in their appearance be detected. Gardeners express the fact by saying that 
the capacity for germination becomes extinct in from twenty to thirty years. But 
what kind of a force is this which may perish without a physical change of the 
substance concerned affording the basis of the extinction? In former times a special 
force was assumed, the force of life. More recently, when many phenomena of plant 
life had been successfully reduced to simple chemical and mechanical processes, 
this vital force was derided and effaced from the list of natural agencies. But by 
what name shall we now designate that force in nature which is lable to perish 
whilst the protoplasm suffers no physical alteration and in the absence of any 
extrinsic cause; and which yet, so long as it is not extinct, causes the protoplasm 
to move, to inclose itself, to assimilate certain kinds of fresh matter coming 
within the sphere of its activity and to reject others, and which, when in full 
action, makes the protoplasm adapt its movements under external stimulation to 
existing conditions in the manner which is most expedient ? 
This force in nature is not electricity nor magnetism; it is not identical with 
any other natural force, for it manifests a series of characteristic effects which 
differ from those of all other forms of energy. Therefore, I do not hesitate again 
to designate as vital force this natural agency, not to be identified with any other, 
whose immediate instrument is the protoplasm, and whose peculiar effects we 
call life. The atoms and molecules of protoplasm only fulfil the functions which 
constitute life so long as they are swayed by this vital force. If its dominion 
ceases, they yield to the operations of other forces. The recognition of a special 
natural force of this kind is not inconsistent with the fact that living bodies 
may at the same time be subject to other natural forces. Many phenomena of 
plant life may, as has been already frequently remarked, be conceived as simple 
chemical and mechanical processes, without the introduction of a special vital 
force; but the effects of these other forces are observed in lifeless bodies as well, 
and indeed act upon them in a precisely similar manner, and this cannot be said 
of the force of life. 
Were we to designate as instinctive those actions of the vital force which 
are manifested by movements purposely adapted in some manner advantageous 
to the whole organism, nothing could be urged against it. For what is instinct 
but an unconscious and purposeful action on the part of a living organism? Plants, 
then, possess instinct. We have instances of its operation in every swarm-spore 
