SCIENCE. 



231 



croscope we are able to-day, to separate in each nervous 

 centre, the sensitive cells from others ot a like kind 

 performing different functions which can be recognized 

 by their shape, dimension and situation. 



It is useless here to go into minute details concerning 

 this point. I will call attention, however, to the fact that 

 each sensitive nerve cell is connected with exterior agents 

 by a long fibre called the cylinder axis, which resembles 

 a lelegraph wire carefully concealed by a layer of fat, 

 and which, surrounded oy numerous proteciing mem- 

 branes, extends throughout portions of the tjouy, and 

 produces sensibility. All these nerve fibres, whose recep- 

 tive apparatus is in the encephalo-medullary mass, are 

 grouped together and form those little white filiments 

 whicn we designate as nerves. If the end of a nerve is 

 touched, or the root, a modification can instantly be de- 

 termined, which carried 10 the nervous cen.res, becomes a 

 sensation. This sensation is, ol course, not always the 

 same, but is in accordance with the determining agent, 

 opiic, acoustic, gustative, e.c. 



If for instance, we cut the nerve which conducts light 

 from the eye to the brain, this sensation will immediately 

 be felt ; but if, on the contrary, one of the skin nerves be 

 cut, intense pain will be experienced. It is not, therefore, 

 as M. Delboeuf very justly remarks, the nature of the ex- 

 citation which determines that of the impression, but the 

 manner in which the brain centre is brought into activity ; 

 so that if the optic and acoustic nerves be cut, united 

 and inverted, a noise would be interpreted by a sensa- 

 tion of light, and vice versa. The sight ot a picture 

 would determine sounds in relation to the brilliancy 

 of the paint employed, while an orchestra would produce 

 colors varying, according to the sounds. Sensations ex- 

 perienced in consequence of exterior impressions do not 

 therefore depend upon the character ot the latter, but 

 upon the nature ol our nervous cells. We do not feel 

 that which occurs upon our body, but only that which 

 takes place in our Drain. If, therefore, all our nerve 

 cells were identical, the exterior world would doubtless 

 produce sensations, but they would be precisely alike, 

 merely differing -in intensity. There are certain animals 

 which exist in this condition. 



M. Helmholtz and other physiologists have calculated 

 the amount of time required lor the transmission of the 

 excitation to the sensitive nerves, and have decided upon 

 thirty metres a second — that is to say, a rapidity equal to 

 an express train advancing at full steam power. Imagine 

 a man whose brain is in Paris while the extremity ot one 

 of his limbs is in Geneva, and we will see that it must re- 

 quire precisely four hours and forty-four minutes tor a 

 sensation to pass from the latter city to the former. 



Given the small distance which separates our extrem- 

 ities from the nerve centres, and the time of transmission 

 is short. It is remarkable, however, that those organs 

 which play the greatest 10/em the preservation and con- 

 servation of the individual, sight and hearing should be 

 placed in close proximity to tne brain. This produces a 

 rapid transmission, and enables a speedy evasion of 

 destructive objects — a disposition evidently acquired by 

 natural selection. It seems, moreover, that the intensity 

 of the impression is in accordance with the distance inter- 

 vening between the excitation and the nerve centre. We 

 may thus explain the extreme violence of neuralgia of the 

 face and head, as compared with that affecting other por- 

 tions of the body. 



All the various forms of sensibility have an analogous 

 basis. The connection and fundamental identity can be 

 demonstrated by tne action ot narcotics. We snail see 

 that this is the inos; general ana cnaracteristic property 

 of life, and mis axiom can ue lully established— that 

 everything which nves, whether animal or vegetable, 

 feels and can be rendered insensible. 



It is a well known lact that certain plants rebound 

 when they are touched. The sensitive one closes its 

 leaves while a great number of carnivorous plants shut 



up like traps as soon as a fly alights upon them, impris- 

 oning and crushing the poor insect which is to serve 

 them as nourishment. The action of day and night has 

 been equally verified in regard to plants. Some flowers 

 only open when the sun shines, while others bloom solely 

 in the dark. It has also been seen that the leaves some- 

 times turn towards the sun, but these phenomena have 

 been called exceptional, many persons even placing them 

 in the category of problematic occurrences, not wishing 

 evidently to open their eyes to facts which they consider 

 humiliating to the animal species. 



Now, however, doubt is no longer possible. Ignor- 

 ance upon this point can no longer be permitted, and 

 every one must know that animals and plants alike pos- 

 sess sensibility. A great philosopher and physiologist, 

 Claude Bernard, first demonstrated this important truth, 

 not by means of tortuous reasoning, but by the brilliant 

 light of experiment. 



Provided with an anaesthetic agent, ether or chloroform, 

 he was able to prove that the highest forms of conscious 

 sensibility and the lowest forms of unconscious sensibility 

 can be successfully affected. When the action of the 

 narcotic begins to take place the ego sleeps and with 

 it, conscious sensibility. That is sufficient for the sur- 

 geon who can then begin to cut and burn without the 

 shadow of an arriere fiensee. 



Upon continuing the introduction of the fumes of ether 

 into the organism, we see all the forms of unconscious 

 sensibility gradually become annulled subsequent to con- 

 scious sensibility. After hiving acted upon tne nerve cell, 

 the anaesthetic destroys the sensibility ot all the tissues, 

 that is to say their vital characteristic, causing them to 

 react upon exterior agents— in one word, it kills the 

 individual. 



If we pass on from the animal to the plant, we find 

 that ether and chloroform act in identically the same 

 manner. Subject the leaves of a sensitive plant to the 

 fumes of either of these agents, and you will be able to 

 handle them without eliciting the slightest movement on 

 their part. They no longer feel the contact of the hand, 

 for knowing as we do that anaesthetics respect the func- 

 tions of movement, we can only attribute this inertia to 

 the impotency of the excitation. 



Let us now take a rapidly germinating seed, such as 

 that of the water-cress and place it upon a sponge soaked 

 in water. In twenty-four hours it will have blossomed 

 into a tiny stem and root. Repeat the experiment under 

 the same conditions of oxygen, water, light and heat, but 

 place the sponge beneath a glass which has been dipped 

 in ether. The seed will remain intact. It is not dead 

 however, it merely sleeps, for if we remove the glass it 

 will recover from its stupor and by the following day will 

 have sprouted. This unseen life possessed by the seed, 

 life which asks nothing more than to make itself ap- 

 parent, is, however, subject to external and internal con- 

 ditions. The first are the necessity of water, oxygen, 

 heat and all physio-chemical conditions ; but there is 

 still something else, internal, inherent to the seed itself 

 and constituting the essence of its life. It is sensibility. 

 Destroy this function and notwithstanding the most fav- 

 orable surroundings, the development will be effectually 

 stopped. 



Do not think that this is owing to any peculiarity of 

 the plant and its embryonic condition, tor a hen's egg, 

 that latent condition of lite of an organism belonging to a 

 comparatively high order, cannot be hatched with any 

 desirable result in an etherized atmosphere. 



Germination, the first vital act of the individual, be it 

 plant or animal, is therefore subject to sensibility and in 

 this function we see it appear for the first time. After- 

 wards it is not difficult to follow it in its course through 

 all the vital acts of the organism. The plant breathes 

 and giows by assimilation, absorbing either the sub- 

 stances contained in the earth, or the carbonic acid in 

 the air. For a long time this gaseous assimilation was 



