Is the character of the actions such that we must believe them to be performed for the sake of their result? The result in question, as we shall hereafter abundantly see, is as a rule a useful one,-the animal is, on the whole, safer under the circumstances for bringing it forth.So far the action has a teleological character; but such mere outward teleology as this might still be the blind result of vis a tergo.The growth and movements of plants, the processes of development, digestion, secretion, etc., in animals, supply innumerable instances of performances useful to the individual which may nevertheless be, and by most of us are supposed to be, produced by automatic mechanism.The physiologist does not confidently assert conscious intelligence in the frog's spinal cord until he has shown that the useful result which the nervous machinery brings forth under a given irritation remains the same when the machinery is altered.If, to take the stock-instance, the right knee of a headless frog be irritated with acid, the right foot will wipe it off.When, however, this foot is amputated, the animal will often raise the left foot to the spot and wipe the offending material away.
Pfluger and Lewes reason from such facts in the following way: If the first reaction were the result of mere machinery, they say; if that irritated portion of the skin discharged the right leg as a trigger discharges its own barrel of a shotgun; then amputating the right foot would indeed frustrate the wiping, but would not make the left leg move.It would simply result in the right stump moving through the empty air (which is in fact the phenomenon sometimes observed).
The right trigger makes no effort to discharge the left barrel if the right one be unloaded; nor does an electrical machine ever get restless because it can only emit sparks, and not hem pillow-cases like a sewing-machine.
If, on the contrary, the right leg originally moved for the purpose of wiping the acid, then nothing is more natural than that, when the easiest means of effecting that purpose prove fruitless, other means should be tried.Every failure must keep the animal in a state of disappointment which will lead to all sorts of new trials and devices; and tranquillity will not ensue till one of these, by a happy stroke, achieves the wished-for end.
In a similar way Goltz ascribes intelligence to the frog's optic lobes and cerebellum.We alluded above to the manner in which a sound frog imprisoned in water will discover an outlet to the atmosphere.Goltz found that frogs deprived of their cerebral hemispheres would often exhibit a like ingenuity.
Such a frog, after rising from the bottom and finding his farther upward progress checked by the glass bell which has been inverted over him, will not persist in butting his nose against the obstacle until dead of suffocation, but will often re-descend and emerge from under its rim as if, not a definite mechanical propulsion upwards, but rather a conscious desire to reach the air by hook or crook were the main-spring of his activity.Goltz concluded from this that the hemispheres are not the seat of intellectual power in frogs.He made the same inference from observing that a brainless frog will turn over from his back to his belly when one of his legs is sewed up, although the movements required are then very different from those excited under normal circumstances by the same annoying position.They seem determined, consequently, not merely by the antecedent irritant, but by the final end,-though the irritant of course is what makes the end desired.
Another brilliant German author, Liebmann, argues against the brain's mechanism accounting for mental action, by very similar considerations.A machine as such, he says, will bring forth right results when it is in good order, and wrong results if out of repair.But both kinds of result flow with equally fatal necessity from their conditions.We cannot suppose the clock-work whose structure fatally determines it to a certain rate of speed, noticing that this speed is too slow or too fast and vainly trying to correct it.Its conscience, if it have any, should be as good as that of the best chronometer, for both alike obey equally well the same eternal mechanical laws-laws from behind.But if the brain be out of order and the man says "Twice four are two," instead of "Twice four are eight,"
or else "I must go to the coal to buy the wharf," instead of "I must go to the wharf to buy the coal," instantly there arises a consciousness of error.The wrong performance, though it obey the same mechanical law as the right, is nevertheless condemned,-condemned as contradicting the inner law-the law from in front, the purpose or ideal for which the brain should act, whether it do so or not.
We need not discuss here whether these writers in drawing their conclusion have done justice to all the premises involved in the cases they treat of.We quote their arguments only to show how they appeal to the principle that no actions but such as are done for an end, and show a choice of means, can be called indubitable expressions of Mind.
I shall then adopt this as the criterion by which to circumscribe the subject-matter of this work so far as action enters into it.Many nervous performances will therefore be unmentioned, as being purely physiological.Nor will the anatomy of the nervous system and organs of sense be described anew.The reader will find in H.N.Martin's Human Body , in G.T.Ladd's Physiological Psychology, and in all the other standard Anatomies and Physiologies, a mass of information which we must regard as preliminary and take for granted in the present work.Of the functions of the cerebral hemispheres, however, since they directly subserve consciousness, it will be well to give some little account.Footnotes Cf.George T.Ladd: Elements of Physiological Psychology (1887), pt.III, chap.
III, 9, 12
Zur Analysis der Wirklichkeit , p.489
Nothing is easier than to familiarize one's self with the mammalian brain.Get a sheep's head, a small saw, chisel, scalpel and forceps (all three can best be had from a surgical-instrument maker), and unravel its parts either by the aid of a human dissecting book, such as Holden's Manual of Anatomy , or by the specific directions ad hoc given in such books as Foster and Langley's Practical Physiology (Macmillan) or Morrell's Comparative Anatomy, and Guide to Dissection (Longman & Co.).
