VARIOUS FLEAS 43 



a time are dangerous, and often lead to blood-poisoning 

 and death. Europeans avoid the burrowing of the 

 jigger by having their toes carefully examined every 

 morning, but black men are less careful. From the 

 West Indies, about thirty years ago, the jigger was 

 earned in ships to West Africa. There it flourished and 

 spread from village to village across Central Africa, 

 decimating the population. It appears to have been 

 carried to a large extent by dogs, in whose skin it 

 flourishes. It has now passed through Africa to India, 

 and we shall no doubt soon hear of its having completed 

 the circuit of the globe. 



A great many kinds of fleas are known, many furry 

 animals having their own special species, which does not 

 leave them to take up its dwelling on other kinds of 

 animal. The common rat has a large flea of its own, 

 which apparently is not the flea which carries the plague 

 from rats to men. It is a " wandering " flea which does 

 this, namely, the Cheops flea. This flea, common in 

 the East but unknown in colder regions, does not stay 

 as one could wish it to do on the rat ; but travels 

 about visiting human beings and dogs, and so carries 

 the plague bacillus from rats to men. In the absence 

 of these fleas plague would be a rat-disease unknown 

 in men. It is probable that we do not nowadays live so 

 thoroughly cheek-by-jowl with rats in Western Europe 

 as formerly, so that even if rats infected with plague 

 and harbouring the Eastern Cheops flea arrive in our 

 docks, the wandering flea is too far off to reach us in 

 our modern houses. 



17. Public Estimate of the Value of Science 



The Royal Society, the full title of which is The 

 Royal Society of London for the Promotion of Natural 

 Knowledge, has its anniversary meeting and dinner on 



