PARASITES FBEE DURING THEIR WHOLE LIFE. 127 



the full-grown insects bring them, whereas the lame of 

 gnats' get their own living; the mother flea sucks for 

 herself first, and then divides the spoil with her larvae 

 which as yet have no feet. For a long time it was 

 thought that the fleas of different animals belonged only 

 to a single species, and consequently that the flea of 

 man was not different from that of a cat or a dog. 



Daniel Scholten, of Amsterdam, in 1815, showed by 

 his microscopical observations, that fleas differ from 

 each other ; and in 1832, Duges of Montpellier, investi- 

 gated the distinctive marks of the various species. The 

 observations of Scholten may be found in "Les 

 Materiaux pour une faune de la Neerlande," by E. T. 

 Maitland. 



The ordinary flea is called Pulex.irritans, and espe- 

 cially attacks man in Europe and in North America ; it 

 may be called a fly without wings, and, together with its 

 congeners, it forms a distinct family under the name of 

 PulicidsB. Van Helmont treated of these insects, and 

 gave directions for making them, just as though he were 

 describing a recipe for pomade. At that time, natural- 

 ists supposed that certain fish could be formed spontane- 

 ously, and that nothing but fermentation was necessary 

 in order to bring forth a crowd of living creatures from 

 this molecular disaggregation. Pleas may, perhaps, 

 some. day find a place in the chemist's shop as well 

 as leeches. We see no reason why homoeopathic 

 bleedings should not be resorted to, as well as homoe- 

 opathic medicines; we should certainly have more 

 confidence in the effects of the bites of fleas, than in 

 the efficacy of remedies subdivided into the millionth 

 part of a grain. 



