236 NATURE STUDY. 



ness, keenness of vision, color protection, will help in the 

 search for food or in the '^scape from enemies; and we find 

 evidences of this special fitness that has come from natural 

 selection — another term for adaptation — on every hand. 

 It adds greatly to the interest of every walk or ride, when 

 once we have come to think about it, and our eyes are 

 opened so that we see. 



A Collection of Fleas. 



The safe arrival of the whaler P'orget-Me-Not at Sidney, 

 Cape Breton, and the repoit that her captain has been in- 

 trusted with the task of obtaining specimens of arctic fleas 

 for Charles Rothschild, suggested a visit to Tring Park, 

 where thousands upon thousands of fleas are kept in his 

 famous zoological museum. Dr. Jordan is in charge of 

 the museum. There were cabinets containing fleas of all 

 forms and sizes from nearly every corner of the world. 

 They number 10,000 or more. 



" Ever}' mammal and bird has a particular kind of flea," 

 said the doctor. " Very many have several different 

 kinds. Thus it appears that the cat flea is different from 

 Ihe dog flea, and the dog flea from the sparrow flea. Each 

 in turn is different from Pulex irritationis, the scientists' 

 pet name for the human flea. So you see," obser\.'ed 

 Dr. Jordan, "that the flea affords more diverse matter 

 for a collection than does any other living creature." 



He than produced some of the gems of the collection. 

 One, the mole flea, is the largest specimen known. He is 

 one-fifth of an inch in length and is named Hypstrichop- 

 sylla talpcs. Another, the most injurious of all fleas, is 

 known as the chigoe or sand flea. Still another is a flea 

 with claws like those of the lobster, which is found on a 

 small South American bird. 



Mr. Rothschild collects his fleas vicariously through 

 agents. Whenever an}- expedition is about to start for a 

 protracted journe}- to a foreign land he engages one of the 

 party to collect species of fleas from mammals or birds that 



