Variations of this kind are observed in the case of all species of snakes. Thus Phisalix rightly insists upon the necessity of always noting, besides the species of snake, the place of origin and the season; for he has himself seen that, as regards French vipers, those of the Jura, for example, produce in the spring a venom almost devoid of local phlogogenic action; while vipers from the vicinity of Clermont-Ferrand, though less toxic, produce much more serious local effects. On the other hand, it has been shown by Th. Madsen and H. Noguchi, in a very interesting study of venoms and anti-venoms,[17] that, when we examine the relation between dose and toxicity, we find that the interval separating the moment of inoculation from that of death diminishes only up to a certain point in proportion as the dose is increased. In the case of the guinea-pig, with 0·0005 gramme of Cobra-venom the interval is 3 hours 75 seconds; but after this, an increase in the dose produces only a relatively inconsiderable acceleration of death. There is therefore no strict ratio between the dose inoculated and the time that elapses until death supervenes. D.--EFFECTS OF VENOM IN NON-LETHAL DOSES. When the quantity of venom introduced into the organism is insufficient to cause death, the phenomena that precede and accompany recovery differ very greatly according as the snake from which the venom was derived belongs to the COLUBRIDÆ or VIPERIDÆ. After a non-lethal bite from a Cobra or Krait, for example, convalescence usually takes place very rapidly, and, apart from the local œdema of the subcutaneous tissue surrounding the wound, which in very many cases leads to the formation of a suppurating abscess, no lasting injury to health is observed. The venom is eliminated by the kidneys, without even causing albuminuria, and sensation gradually returns, in twenty-four or forty-eight hours, in the part affected by the original lesion. If the bite has been inflicted by a Viperine snake, the local lesion, which is much more extensive, almost always results in the formation of a patch of gangrene. Hæmorrhages from the mucous membranes, and sanguineous suffusions into the serous cavities, such as the pleura or pericardium, may supervene more or less slowly. Pulmonary infarcts are sometimes produced, as well as desquamation and hæmorrhage from the kidneys, albuminuria, or hæmaturia. These lesions, which are more or less severe, last for several days, and then slowly disappear after a period of true convalescence. In many cases they leave behind them traces which last for months and even years, and they then more or less affect the health of the subjects according to the organs that were most seriously affected. In certain cases, in domestic animals such as dogs, and more rarely in man, after recovery from the bite of a viper, total or partial loss of sight, smell, or hearing, has been observed. Such results, however, are fortunately exceptional. CHAPTER VII.