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240 DESIGN IN NATURE
§ 45. Irritability.
This term is erroneously applied to both plants and animals. Plants and animals in a healthy normal con-
dition cannot be said to be irritable. They are sensitive ; but this is quite another matter. IrritabiUty, strictly
speaking, can only be applied to unhealthy and abnormal plants and animals. The term irritability was first
employed to indicate that something in plants and animals which caused them to respond to external stimulation.
The term involved a theory, and, to prove the theory, a second theory— namely, that of artificial stimulation—was
invented.
§ 46. Irritability plus Stimulation.
The theories of irritability and stimulation are necessary to each other. They take for granted that plants
and animals require to be jogged into activity by something outside of themselves. They ignore the life, spon-
taneity, and independence of plants and animals, and regard them as mere automata, which they certainly are not.
To make this matter quite plain, it is only necessary to state that healthy plants and animals can, and do,
habitually perform all their normal functions as apart from both irritability and extraneous stimulation.
It is not denied that healthy plants and animals, and parts thereof, respond to electric and other stimulation,
such as pricking, cauterisation, the application of mustard, acids, &c. This fact, however, does not prove that the
plants and animals are irritable, and that they can only act in response to stimuli. Healthy plants and animals,
as explained, are sensitive, and, as a consequence, shrink from violent treatment. As further explained, they
perform all their functions spontaneously and independently, that is, as apart from irritability and stimulation.
Moreover, the results obtained by artificial stimulation are not identical with similar results obtained in plants
and animals which are not artificially stimulated. The most that can be said is that in certain cases, and under
certain circumstances, artificial stimulation produces results akin to, but not identical with, results obtained by
natural stimulation, which has its origin in the original endowments and life of the individual. If a muscle be
pricked, or a nerve excited by an electric shock, it cannot be shown that the results obtained are identical with
those witnessed in natural muscles and nerves not so pricked and excited. In the one case, the stimulation is
artificial and from without :
in the other case, it is natural and from within. The modus operandi is essentially
different. The mechanical treatment of hving plants and animals as if they were automatic machines has great
attractions for a large number of enthusiastic modern physiologists. They pride themselves on obtaining what
they are pleased to designate exact results. They are ambitious to measure, to weigh, to demonstrate, and conscientiously
record everything ; and they inconsistently, in many cases, resort to the employment of the most dehcate,
complicated, and expensive instruments, which they use in a clumsy, careless, inexact manner. Their modes of
experiment are inexact and crude to a degree. They profess to obtain the secrets of the most sensitive tissues and
organs in plants and animals by the employment of every conceivable kind of stimulus, and by hacking them about
with knives, scissors, needles, &c., and torturing them until they are abnormal to an alarming extent, in the vain
hope that they are imitating nature. I have seen one of th* so-called exact mechanical physiologists constructing
a chart of the power exerted by and the movements characteristic of the heart of a frog by partially detaching the
organ from the body, by lacerating and displacing its nervous and muscular fibres, and by attaching the latter to
a balance furnished with a stile or pen and connected with a recording cylinder. Nothing could possibly be more
untrustworthy and incongruous. There was the usual employment of delicate, complicated, exact instruments with
the most violent and barbarous, and, I am afraid I must add, ignorant procedure. The heart was deprived of its
blood supply, the ganglia of the heart were displaced, torn, and abnormally excited, and, in many cases, destroyed ;
and the cavities of the heart, especially that of the ventricle, were opened and partly teased out. To crown all,
the lacerated, fatally injured, bloodless heart was occasionally jogged into spasmodic activity by the apphcation of
electrical stimulation. Here was an imitation of nature's methods with a vengeance ; yet the results thus artificially
and ruthlessly obtained were duly published and paraded in a scientific journal as an exact physiological research.
On another occasion I saw two well-known scientists open the abdomen of a rabbit and literally tear, and maul
beyond recognition, the solar plexus with needles to discover the functions of the plexus by direct 'experiment.
These are examples of badly directed experiments and faulty manipulation, but they illustrate the methods in
many cases followed by the mechanical school. As compared with natural methods, the results obtained by even
the most experienced and adroit experimenters are, at the best, doubtful, and to be received with the extreme of
caution. It cannot be otherwise. If animal tissues and organs are lacerated or stimulated to any great extent, the
circulatory, nervous, muscular, and other systems are abnormally disturbed, and a perfectly normal result, under
the circumstances, is impossible.