PLAGUE, RATS AND FLEAS. 267 



stable door, and immediately one's trousers were covered with fleas. 

 These fleas were Pulex felis, which we saw was the common dog flea. 

 Here, again, driven by hunger, in the absence of the dog, man was 

 attacked. Herein lies, too, the explanation of the swarms of fleas one 

 reads and hears of in dak bungalows in India. Somebody has been 

 there before with dogs. The dogs left with their master, but left their 

 fleas behind. The bungalow was shut up for a time, another sahib 

 entered, this time without a dog. He is immediately attacked by the 

 fleas. 



Finally the proof was completed by the following experience for 

 which I am indebted to the Revd. J. H. Lord. On April 20th last 

 year he sent me some fleas which had been caught on man in a house 

 which was infected with plague under the following circumstances. 

 About the 6th or 7th of April, rats began to die in large numbers in the 

 chawl in which this house was situated. Suddenly the deaths amongst 

 rats ceased and on April 11th the people became troubled with fleas. 

 The fleas were so numerous that they had to quit their rooms and sleep 

 out in the verandah. While living in the verandah on April 17th one 

 of the inhabitants of the particular room in which the fleas were taken, 

 became infected with plague. Another case occurred on the same day 

 in a room adjoining. This room was separated from the aforementioned 

 room only by a partition 6^ feet high. On the same day the information 

 about this chawl came to Mr. Lord. He succeeded in getting the 

 people who inhabited the room where the above case occurred to collect 

 some of the fleas which they said troubled them, and he sent the collec- 

 tion to me on April 20th. An examination of this collection was most 

 instructive. Now I must tell you that on previous occasions, of 246 

 fleas which were caught on man under normal conditions I had only 

 found one rat flea, Pulex cheopis. But of the collection of 30 fleas 

 caught on man under the circumstances above recorded no less than 14 

 of these were rat fleas. Nothing could be more striking. 



Now what is the explanation of such unusual invasion of the guinea- 

 pig and man by rat fleas ? You note, that in both cases, a few days 

 before, rats had been noticed dead in considerable numbers ; then no 

 more rats were found dead, and plague broke out in the guinea-pigs 

 and men. Taking this in conjunction with the facts above recorded 

 regarding the starved fleas, I think the explanation is that, either the 

 rats had been almost completely exterminated by the plague, or what is 



