refer to the intercommunication between New York and Europe in the year of cholera, 1873. In that year, according to the register of the offices at New York, there were 700 vessels which arrived from different parts of the world, giving an aggregate of 316,956 individuals, but of these 266,055 came from Europe. Of these, 113,920 came from England, which was free from cholera; from the remainder of Europe the numbers were 152,135, and about 400 vessels served to convey the individuals, making up the last figures, from ports infected with cholera. If we inquire into the statistics, we find that cholera chiefly occurred on four vessels only. Eleven cases were registered from the Westphalia; one fatal case from the Ville du Havre; from the Washington three fatal cases; and from the Holland one fatal case.
Although the chances of contagion aboard ship are very favorable, yet how small was the number of cases of cholera! Take the ship with eleven cases, and we find that they belonged to two German families only; two died during the voyage, nine were landed on Dix Island, and of these but one died and the rest recovered. How is it conceivable that cholera should have confined itself to two families without attacking others? I believe that both families had contracted cholera before going on board; indeed, an epidemic may occur in a ship provided the passengers have all come from a place where cholera exists. The contagionists have, however, replied that some remarkable epidemics have happened on board ship, which could not be explained on the above-mentioned view. It is a question whether cholera can infect on board ship. The contagionists take facts conveniently; they select those instances which occur least frequently and adopt them, to the exclusion of the great majority of instances which tells against them. I recall the articles which I wrote in the "Vierteljahresschrift für öffentliche Gesundheitspflege" and in the "Zeitschrift für Biologie" to prove that I have thoroughly investigated the nature of epidemics of cholera on ships. Rumors of false returns concerning cholera on board ship have been bruited. But these falsifications can hardly be committed when an epidemic occurs during a voyage. It may be said that my instance of 1873 does not disprove the contagiousness of cholera. Cholera, like small-pox, does not attack every one who is brought into relationship with it. If even a few instances of contagion were proved to have occurred on board ship, we should have to admit the contagiousness of the disease.
I do not doubt that instances may exceptionally be found among infectious diseases in which the behavior is essentially the same as that of cholera on the ships going between Europe and New York. But the question is. How do such cases generally, not exceptionally, behave? Vaccinated persons maybe brought into contact with cases of small-pox without fear of infection; and, at times, individuals who have not been vaccinated may come in contact with small-pox without taking the disease. As a rule, however, small-pox on board ship be-
