VITAL FORCE, INSTINCT, AND SENSATION. 51 
of its own of a certain specific constitution. And, further, we must assume that 
this specific protoplasmic constitution is transmitted from one generation to another, 
so that the protoplasm of the oleander, for example, had exactly the same constitu- 
tion thousands of years ago as it has to-day. Lastly, we must assume that each 
special kind of protoplasm has the power to reproduce its like, ever anew, from 
the raw materials occurring in its environment. 
VITAL FORCE, INSTINCT, AND SENSATION. 
The phenomena observed in living protoplasm, as it grows and takes definite 
form, cannot in their entirety be explained by the assumption of a specific con- 
stitution of protoplasm for every distinct kind of plant; though this hypothesis 
will again prove very useful when we inquire into the origin of new species. 
What it does not account for is the appropriate manner in which various functions 
are distributed amongst the protoplasts of a cell-community; nor does it explain 
the purposeful sequence of different operations in the same protoplasm without 
any change in the external stimuli, the thorough use made of external advan- 
tages, the resistance to injurious influences, the avoidance or encompassing of 
insuperable obstacles, the punctuality with which all the functions are performed, 
the periodicity which occurs with the greatest regularity under constant condi- 
tions of the environment, nor, above all, the fact that the power of discharging 
all the operations requisite for growth, nutrition, renovation, and multiplication 
is liable to be lost. We call the loss of this power the death of the protoplasm. 
It ensues upon assaults from without if they succeed in destroying the molecular 
structure so entirely as to render reconstruction impossible; but, furthermore, 
death may take place without external cause. 
If cells of the blood-red alga, previously mentioned as allied to the red-snow, 
are collected from hollows in stones, casually full of rain-water, and are kept 
dry for weeks and then again moistened, the water is found to have a very power- 
ful effect. The protoplasm becomes mobile, and swarm-spores are formed which 
put forth vibratile cilia, propel themselves about for a short time in the water, 
and then settle down in some favoured spot, draw in their cilia, come to rest 
and divide, producing offspring which again are motile. This alga may be kept 
dry for months, nay even over a year, and still its cells exhibit the movements 
above described when put into water. But if a mass of it is preserved under 
these same conditions for many years and then moistened, the little cells will, it 
is true, take up additional water, but motile cells are no longer formed. The 
cells do not move, nor grow, nor divide, but gradually become discoloured; are first 
disintegrated and then dissolved. We say then that in them life could no longer 
be recalled, and we deseribe them as dead. 
The same thing is observed in great cell-communities. The seeds of many species 
of plants preserve the capacity for germination for an incredibly long period, especially 
when kept in a dry place. If after ten years such seeds are transferred into 
