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BARDWICKE'S SCIENCE-GOSSIP. 



ON THE DEVELOPMENT OF A FLEA'S EGG. 

 [PULEX IRRITANS.) 



MICROSCOPISTS have perhaps been the only 

 class who ever regarded this insect with any 

 degree of favour, and that, only of a posthumous 

 kind, when duly balsamed, and prepared as an object 

 of investigation for their favourite instrument, but its 



occasionally be seen in astonishing numbers, still,, 

 nothing to equal the myriads infesting warehouses 

 and other buildings in tropical countries, on emerging 

 from which the visitor finds it desirable to brush 

 away the superfluous swarm from his clothing. How 

 they subsist, seems a mystery, as a sanguinary diet 

 appears to be impossible. 



Mr. W. M. Williams writes in Science-Gossit, 

 December, 1884, " I have found fleas in limestone 



Fig. 169. 



ng. 172. 



Fig. 176. 



Fig. 171. 



Fig- 173- 



Fig. 174. 



'.:/ 



Fig. 178. 



Fig. 177. 

 Figs. 169 to 179 showing stages in the Development of the Common Flea [Pule.tr irritans). 



life-history up to maturity, beyond which it might not 

 be altogether pleasant to pursue it, is of the most 

 interesting and instructive character ; and as least is 

 popularly known about the earlier period of the flea's 

 existence, I purpose in this paper and accompanying 

 sketches to submit only what is the result of direct 

 and careful personal observation, so far as the nascent 

 stages of the development of P. irritans are con- 

 cerned. 



In our climate, as compared with warmer regions, 

 the supply is not exuberant, and a careful housewife 

 soon reduces it to a minimum, but, in hot weather, 

 among the dried weed by the seashore, fleas. t may 



caverns, or, rather, they have found me, where no 

 other supplies of food existed, excepting the animal 

 matter that may have remained in the fossils of which 

 the limestone was chiefly composed." Such a diet 

 would, however, be more suitable to the mandibular 

 than the suctorial stage of the flea's existence ; possibly 

 after completing its metamorphosis pulex may live 

 long enough to deposit eggs, without any opportunity 

 of practising phlebotomy, and so maintain its swarms 

 without diminution. 



In point of size our familiar P. irritans is a mere 

 pigmy compared to its relative Pulex imperaior, a 

 solitary example of which appeared most inexplicably 



