574 ACUTE INFECTIOUS DISEASES. 



possibiity of its doing so again. Such reasoning is idle. We know 

 nothing about the first development of measles, arid the fact, observed 

 wherever it is possible to watch carefully the commencement and 

 spread of the disease, that measles never occurs without a case having 

 been brought in from somewhere else, justifies us in concluding that 

 the same thing occurs where it is not possible to detect infection direct- 

 ly. It is just the same with syphilis ; we know that at the present 

 day it is only propagated by transfer ; the question how the first case 

 of syphilis originated lies outside of the circle of physical investiga- 

 tion. The infecting material which induces measles has not been dis- 

 covered, either chemically or microscopically. We do not even know 

 certainly whether it be organized or inorganic, and the hypothesis, that 

 the infection is due to the transfer of small, imperceptible, vegetable 

 organisms, is only to be preferred to other hypotheses, because it 

 agrees better with the facts. I shall only mention a few of the rea- 

 sons for this hypothesis. The period of incubation, that is, the day 

 or week intervening between the infection and the outbreak of the 

 malady, speaks against the infection being caused by substances which, 

 from their chemical or physical peculiarities, are injurious to the organ- 

 ism. If such a substance were transferred, its injurious effects would 

 appear at once, or in a very short time, and the infected person could 

 not remain free from all signs of disturbance for from eight to fourteen 

 days, and then have these suddenly break out with great severity. 

 But if healthy persons be infected by measles patients, through micro- 

 scopic organisms, the period of incubation is much more readily under- 

 stood ; for it is easy to suppose that these organisms are transferred 

 in too small numbers to do harm, but that they multiply in the in- 

 fected person, and immediately after this process, which is completed 

 in a certain time (the period of incubation), their injurious influence is 

 made manifest. A further reason for supposing that measles-poison 

 is organized, is its reproduction in the bodies of the infected patients. 

 For instance, in an epidemic in the Faroes observed by JPanum, one 

 case that was introduced infected the attendants of the patient ; these 

 infected other inhabitants of the island, and, finally, in the course of 

 seven months, 6,000 persons, out of a population of 7,782, were at- 

 tacked. If the observations of Hallier should prove correct, the con- 

 tagious principle of measles has been recently discovered by the micro 

 scope. In the blood and sputa of measles patients, Hallier found 

 microscopic cells of a fungus which grew on various substrata, but was 

 always the same fungus, the mucor muado (verus) of Fres. It is cer- 

 tain that the blood, tears, and secretion of the air-passages, are vehicles 

 for the contagion ; for inoculations made with these fluids have induced 

 measles hi previously healthy persons. But, as the disease most fre 



