[79] It is impossible here to enter into a detailed consideration of the various views held with regard to the formation of antitoxins. It is needless to remark that the whole matter is one of abstruse technicality and intricacy. These antitoxic bodies gradually increase in the blood and tissues, and their action falls into two groups: (_a_) _antitoxic_, which counteract the effects of the poison itself; and (_b_) _antimicrobic_, which counteract the effects of the bacillus itself. "In one and the same animal the blood may contain a substance or substances which are both antitoxic and antimicrobic, such, for example, as occurs in the process of the formation of the diphtheria and tetanus antitoxic serums" (Sidney Martin). [80] Types of bodies possessing positive chemiotaxis for bacteria are the salts of potassium, peptone, glycerine. [81] Negative chemiotaxis is illustrated in alcohol, and free acids, and alkalies. [82] The friend of Addison and Pope, who married Mr. Edward Wortley Montagu in 1712, and on his appointment to the ambassadorship of the Porte in 1716 went with him to Constantinople. They remained abroad for two years, during which time Lady Wortley Montagu wrote her well-known Letters to her sister the Countess of Mar, Pope, and others. [83] Crookshank, _History and Pathology of Vaccination_. [84] An exhaustive account of vaccine may be found in the Milroy lectures delivered in 1898 at the Royal College of Physicians by S. Monckton Copeman, M.D. [85] Crookshank, _Bacteriology and Infective Diseases_; Virchow, _The Huxley Lecture_, 1898. [86] To shorten this period Dr. Cartwright Wood has adopted a plan by which time may be saved, and 200 cc. injected say within the first two or three weeks. This is accomplished by using a "serum toxin" (containing albumoses, but not ferments) previously to the broth toxin, an ingenious method which we cannot enter into here. [87] At the conclusion of the operation the cannula is removed from the jugular vein, and the wound is closed by the valvular character of the slit in the skin and vein and the elasticity of the wall of the vein. No stitching or dressing is required. Indeed, it is striking to observe in the horse an entire absence of pain throughout the proceedings. [88] The term _unit_ is used as a standard measurement. This means the amount of antitoxin which will just neutralise ten times the minimum fatal dose of the toxin in a guinea-pig (250 grams toxin to kill on the fourth day). If 1 cc. of the antitoxic serum is required for this, one unit is contained in 1 cc.; if 0.01 cc. is sufficient, then 100 units are contained in the cc. Not less than 1500 units should be administered for a dose, and repeated every twelve hours. In severe cases two or three times this amount may be given.