ACUTE EXANTHEMATA. 329 



tained in the nasal mucus, the conjunctival secretion, and 

 the sputum of those suffering from measles, and, as 

 experimental inoculation appears to have shown, also in 

 the blood. The contagium is taken up through contact 

 with the sick, or as is generally accepted clinically 

 through inhalation of the exciting agent. The persistence 

 of the virus of measles is not so marked as that of small- 

 pox or of scarlet fever. In a dry state the virus of measles 

 is said to persist for about six weeks. Measles is rarely 

 conveyed by means of articles of clothing, linen, etc., and 

 not for long distances. The infectivity of measles exists as 

 early as the last days of the period of incubation which is 

 between eight and ten days and in the stage of eruption. 

 After the exanthem has entirely appeared, the danger of in- 

 fection rapidly subsides. 



In measles also a large number of bacteria have been 

 found, but, above all, again cocci, which have also been 

 demonstrated in the blood. None of these observations 

 is worthy of consideration, because they depend upon 

 accidental or secondary infection or upon contamination. 



The immunity established by recovery from an attack of 

 measles is rather active and enduring. Only thirty-six 

 cases are recorded in the literature in which two attacks 

 occurred, and only one with three attacks. 



Scarlet Fever. The virus of scarlet fever is much more 

 resistant than that of measles. It adheres for months to 

 the clothing worn and the rooms occupied by the sick. It 

 appears, further, to possess considerable resistance to tem- 

 perature-influences. Infection with scarlet fever, in accord- 

 ance with clinical experience, occurs principally through 

 direct contact with the sick or with articles belonging to 

 them, but also through breathing of the air in rooms satur- 

 ated with the virus of the disease. The period of incubation is 

 of varying duration (from two to twenty-four days). Even 

 toward the end of this period, according to Gerhardt, scarlet 

 fever is infective, and it remains so until the cessation of 

 desquamation and for weeks longer. Wherein the infective 

 material resides, whether in the secretions, in the blood, or 

 in the cutaneous scales, is not known. Some observers 

 claim to have transmitted scarlet fever by inoculation, while 

 others have failed to induce the disease experimentally by 

 means of the blood, the scales, etc. There is much in the 

 clinical picture of scarlet fever, especially the nephritis, in 



