The writer's theory as to the action of snake-poison, formed, in the first instance from observations made at the bedside of his patients only, is thus confirmed by experiments specially instituted by him for that purpose. Further proof of its correctness we have in the brilliant results of the strychnine treatment of snakebite in Australia, which is the outcome and practical application of this theory. In those desperate cases more especially, reported from all parts of the colonies, in which death was imminent, and pulse at wrists as well as respiration had already ceased, the strychnine injections could not possibly have effected complete recovery within a few hours if the structure of the nerve centres had been impaired or blood changes brought about incompatible with life.
Feoktistow's experiments, made with viper poison, fully bear out the correctness of the writer's theory, besides proving that there is no essential difference between the action of the viperine and colubrine poisons. He proved conclusively that snake-poison does not destroy protoplasm or interfere with infusorial life, that injected into the heart of a mollusc it causes an almost immediate cessation of its action, that hypodermic injections of it in fish produce contraction of the pigment cells and bleaching of the integuments, followed by asphyxial respiration, general paralysis and death. Similar results were observed on frogs. In mammals the symptoms were: dyspnoea, asphyxia, paresis and paralysis of the lower extremities with succeeding general paralysis, sometimes tonic and clonic convulsions, hæmorrhages from bowels, lungs, nose and bladder, and finally complete paralysis of respiration and of heart.
Action of Snake-Poison on Special Nerve Centres.
It must be borne in mind that the symptoms as about to be detailed are successive only to some extent in the order presented. They commence generally at the lower part of the spinal cord, but immediately afterwards, if not simultaneously, are ushered in with great rapidity from other centres, masking each other and rendering it extremely difficult to observe and analyse them separately. They are also very variable through the poison concentrating its action on special centres, leaving others comparatively intact, and this not only when from different varieties of snakes, but also from snakes of the same variety. Another element increasing the difficulties of correct analysis are the depressing effects of fear, inseparable in all but the strongest minds from the consciousness of having been bitten, and so similar in appearance to those of snake-poison, that sometimes it is by no means easy to decide which of the two is in operation, and that only those cases are of real value to the observer from which this element of fear is completely excluded.
A.—Action on the Anterior Cornua of the Spinal Cord.
The anterior cornua are almost invariably the first of the motor-centres attacked by the snake-poison, the affection (commencing with paresis and in serious cases generally culminating in paralysis) beginning in the lumbar ganglia and taking an upward course. The lower extremities feel unnaturally heavy and a paretic condition of the muscles supervenes simultaneously on both sides. The walk becomes unsteady and staggering, very similar to that of persons under the influence of large doses of alcohol. By a powerful effort of the will, however, persons in this condition are often able to walk and even run for some distance, especially if by prompt ligature the absorption of the poison has been checked. As the affection proceeds, though still able to move the legs in a sitting posture, they are unable to rise again. Ere long even sitting up becomes impossible and they collapse helplessly. At this stage sensation is still intact, and reflex action, by pricking the skin, &c., still takes place. The upper extremities generally retain the power of voluntary motion, even after the muscles of the neck have become paretic and the head is held up with difficulty or sinks to one side.
With birds, according to Feoktistow, the reverse is the case. The wings are usually first attacked, or paresis comes on in wings and legs at the same time.
B.—Action on the Medulla Oblongata.
a.—The Vaso-Motor Centre.
Whilst the voluntary muscles are thus brought under the influence of the poison, symptoms denoting the invasion of the oblongata are rapidly developing. The first of these is the deadly pallor and ashy hue of the cold skin, evidently due to the blood receding from the surface, a condition not unlike that obtaining in extreme anæmia. As persons in this state complain of an agonising feeling about the heart and of deadly faintness, a paretic condition of the heart suggests itself as the most obvious cause, more especially when taken in conjunction with the small, frequent, and compressible pulse. But though the heart muscle is no doubt participating in the general paresis, the condition of the surface of the body is in reality one of anæmia. The blood, even at this early stage, begins to accumulate in the large veins of the abdomen, which expand gradually in consequence of the diminishing motor force supplied by the splanchnicus, keeping them in the normal state of contraction when intact and having its centre in the medulla oblongata. When this large vaso-motor nerve is cut in animals anywhere in its course, the veins of the abdomen become distended enormously. The animal is, so to say, bled into its own belly.