152 2)r, Klein [May 27, 



As an illustration of the second kind (viz. not probably from a 

 human source) I will refer to the outbreak of scarlet fever in Oxford 

 in the sjiring of 1882, recorded by Dr. Darbishire : in the St. Bartho- 

 lomew's Hosjntal Eejwrts, vol. xx. The substance of Dr. Darbishire's 

 Eeport is this : — Three cows were kept by those who sold the milk, 

 and nine houses, containing 85 persons in all, were supplied morning 

 and evening ; the milk was never stored, as there was generally barely 

 enough at each milking for all the customers. In the house to which 

 the cows and paddock belonged there was a case of diphtheria in a 

 young lady; she was removed to the infirmary on March 1. The 

 cowman had a child ill with scarlet fever in his cottage from 

 February 27 till March 3. On March 3 Dr. Darbishire had this 

 child removed to the hospital and the cowman's cottage thoroughly 

 disinfected ; the cowman left his cottage to sleep in lodgings near, 

 the care of the cows having been handed over to another man, en- 

 gaged for that purpose. Now, if the milk had become infected from 

 either of these two cases (one diphtheria and the other scarlet fever) 

 this must have occurred for the first before March 1, for the other 

 before March 3 ; and as the period of incubation of scarlet fever is 

 known to be as a rule less than seven days, it follows that March 3 

 being the last day on which the milk could have received the con- 

 tagium from a human being, March 10 would be the last day on which 

 scarlet fever could have been produced by that milk, the majority of 

 cases of scarlet fever must have occurred before that day, as one 

 cannot assume that in all these cases the period of incubation was 

 protracted to such length as seven days. But mark what really did 

 happen. Dr. Darbishire states that no case occurred till March 10, 

 on which day two cases of sore throat and one case of scarlet fever 

 occurred; on March 11, one case of sore throat; on March 12, two 

 cases of sore throat and one of scarlet fever ; on March 13, four cases 

 of sore throat and two of scarlet fever ; on March 15, one case of sore 

 throat and one of scarlet fever ; on March 16, two cases of sore throat 

 and one of diphtheria; on March 17, one case of sore throat; on 

 March 18, one case of sore throat. Now, all these cases were proved 

 by Dr. Darbishire to have been caused by that milk. There occurred 

 subsequently other cases, but these were traced to have been due to 

 secondary infection from person to j)erson. This is a good illustra- 

 tion of a milk epidemic in which the milk most probably was not 

 fouled by human agency ; and there are other milk ej^idemics which 

 on analysis of dates lead to the same conclusion. Tbe infection of 

 this milk was probably brought about, as I shall show you hereafter, 

 in some other way. 



As an instance of the third kind — viz. where milk has clearly not 

 been infected from a human source — I will refer to Mr. Power's 

 Eeport in 1882 on an epidemic outbreak of scarlet fever in St. Giles's 

 and St. Pancras. " The disease was distributed with a milk service 

 derived from a Surrey farm. In this case two facts could be 

 affirmed : the one that a cow recently come into milk at this farm 



