The Human Machine 
intricate than this food-catching reac- 
tion of Venus’ Fly-Trap and the frog. 
The principal difference between these 
three living mechanisms is rather a 
difference in the range of activation by 
environment, resulting in the frog and 
in man in a larger number of reactions 
which in turn involve more complex 
effector mechanisms than are possessed 
by the fly-trap. Each reaction of man 
doubtless has more component parts 
than each reaction of Venus’ Fly-Trap, 
just as a large house contains more 
bricks than a small house.2 The most 
complex machine ever invented by man 
looks like a grotesque monster to the 
savage; yet its complex movements are 
compounded of the two simple move- 
ments of translation and rotation.” 
THE WORKING OF THE MACHINE 
If we similarly try to analyze the 
reaction of the fly-trap, we find three 
distinct stages: 
1. The application of an adequate 
stimulus from without, 7. e., the touch 
of a fly. 
2. Conduction of this stimulus from 
the tip of the sensitive filament to the 
motor mechanism of the plant. 
3. The chemical and motor end effect, 
involving all the acts and organs used 
in closing the lobes and the killing and 
digestion of the insect. 
“In the three separate stages of 
adequate stimulus, conduction and end 
effect which compose the reaction of 
Venus’ Fly-Trap, we find all the essen- 
tial factors which enter into the life 
activities of man. Under adequate stim- 
ulus, for instance, are included the 
485 
activating stimuli produced by heat 
and cold, dust, débris, microdérganisms, 
food, air, water, light, poisons, blows— 
and by certain physical and chemical 
changes within and without the body, 
to which man through ‘evolution’ has 
become adapted through the creation of 
an adaptive response. Conduction is 
supplied by the central and autonomic 
nervous systems, that is, by the organs 
of touch, taste, sight, smell, hearing, 
pain, and by the chemical receptors 
for the initiation of certain reactions of 
chemical control. End effects are found 
in all the vital processes of motion and 
emotion, muscular activity, chemical 
change, psychic states, growth, nutri- 
tion, reproduction, thought, invention, 
social forms, government, war, religion, 
business, in short, in all the activities 
by which man’s life is distinguished 
from the immobility of the rock.”’ 
Such is the attitude toward life of 
the mechanistic school. It is, of course, 
open to criticism, but this is not the 
place to criticize it. Let us rather 
examine the details. 
“As we have seen, the presence of the 
adequate stimulus is the first requisite 
for reaction. As the lobes of the fly- 
catching plant close only upon the 
arrival of the insect stimulus, so every 
conceivable act, thought, or function, of 
the human body, requires an adequate 
stimulus for its manifestation, that. 
manifestation depending absolutely 
upon the previous experience of the 
organism or of its species with that 
stimulus. That is, the response to any 
stimulus depends wholly upon the 
biologic necessity which led to its 
oe 1h) aa : 
POV ax 
? It is well known that Venus’ Fly-Trap, the sensitive plant (Mimosa pudica), and other plants 
possessing the power of motion can be chloroformed, when their movements are stopped just as in 
animals. 
On this point Dr. Crile contributes the following note giving a ‘“‘comparison of anesthesia 
in plants possessing a motor mechanism and in animals:;”’ 
“In peripheral nerves after exposure for varying periods of time to vapors of the various fat 
solvent anesthetics, e. g., chloroform, ether and ethy] alcohol, there is an increase in the amount of 
potassium in the medullary sheaths as shown microchemically by the potassium reagent of 
Macallum. A similar increased amount can be demonstrated as the result of mechanical or 
chemicalinjury. In those plants possessing a motor mechanism, e. g., Mimosa pudica and Dionaea 
muscipula, after exposure to the same fat solvent anesthetics there is a marked increase in the 
demonstrable potassium compounds. This increase occurs in the guard cells, in the chlorophyll 
granules, in certain modified conducting elements, but to the greatest extent in those areas of the 
plant which are most active in producing motion and which upon stimulation show a considerable 
turgor. Lipoid substances as demonstrated by osmic acid and scarlet red have the same dis- 
tribution as the potassium compounds. In plants asin animals the lipoid substances which contain 
potassium, e. g., lecithin and cholestrin, after the application of these anesthetics become so 
altered in their physical constitution that the contained potassium compounds can enter into the 
chemical combination with the reagent applied.” 
