9(i PHYSIOLOGY AND TOXICOLOGY 



the blood, and tlivoiigh its degradation, perhaps, of affecting the whole circulating 

 fluid, we are naturally inclined to ask whether this power may not also be invoked 

 to explain even the ultimate nature of the sudden cases of death from the venom. 

 If, for instance, a pigeon is struck by a snake, and dies in thirty seconds, its tissues 

 normal in appearance and its blood unaltered, have we any logical right to infer 

 that the blood may have been inappreciably, but fotally, altered, so as to be unable 

 to sustain the life of the tissues which it feeds ? Is it this possible, but impercept- 

 ible, change in the blood which acts to produce those losses of irritability in the 

 nerve-centres which we have been led to regard as the proximate cause of early 

 and rapid death ? If such be the case, then the suddenness of the genercd change in 

 the blood must account for the failure of life, because it can be shown that animals 

 whose blood is considerably altered may live for some time, or even survive to 

 renew and refibrinate their vital fluids. 



The cause of death in chronic or secondary -poisoning may, with propriety, then, be 

 referred to the incipient putrefactive changes which affect the blood, as well as to 

 the continued influence of the agencies which first act to depress the heart's action, 

 and destroy nerve function. 



The cause of death in the acide cases, where the result is so sudden that no change 

 is perceptible in the blood in the vessels, is amply explained in the preceding pages. 

 But, while we ai-e able to state where death begins, and in what order the func- 

 tions succumb, we are still far fi'om knowing why, or- precisely how, this or that 

 structure is affected. The proximate causes are open to exjDerimental study, the 

 ultimate reason, as we have seen (page 95), is as yet unknown. 



Summing up, then, what we have learned of the acute form of poisoning, we 

 may feel justified in concluding, 1st. That the heart becomes enfeebled shortly after 

 the bite. This is due to direct influence of the venom on this organ, and not to 

 the precedent loss of the respiratory function. Notwithstanding the diminution of 

 cardiac power, the heart is usually in motion after the lungs cease to act, and its 

 tissues remain for a time locally irritable. The paralysis of the heart is, thei'efore, 

 not so complete as it is under the influence of upas or corroval. 



2d. That in warm-blooded animals, artificial respiration lengthens the life of the 

 heart, but does not sustain it so long as when the animal has died by wo.orara, or 

 decapitation. 



3d. That in the frog, the heart-acts continue after respiration has ceased, and 

 sometimes survive until the sensory nerves and the nerve-centfes are dead, the motor 

 nerves alone remaining irritable. 



4th. That in warm-blooded animals respiration ceases, owing to paralysis of the 

 nerve-centres. 



5th. That the sensory nerves, and the centres of nerve power in the medulla 

 spinalis and medulla oblongata, lose their vitality before the efferent or motor nerves 

 become affected. 



6th. That the muscular system retains its irritability in the cold-blooded animals, 

 acutely poisoned, for a considerable time after death. 



7th. That the first eflect of the A'^enom being to depress the vital energy of the 

 heart and nerve-centres, a resort to stimulants is clearly indicated, as the only 

 rational mode of early constitutional treatment. 



