786 Marvels of the Universe 
evidence which tends to show that fleas were once 
two-winged flies, which, owing to the development 
of the parasitic habit, have so completely lost their 
functionless wings that even the entomologist 
himself can now scarcely trace their rudiments. 
That explanation probably throws some light on 
the manner in which the various flea species 
became associated with special and widely-removed 
hosts, for coming of a family of winged flies they 
would have ample opportunity of seeking and 
selecting those animals best adapted to their 
requirements. 
With the parasitic habit degeneration necessarily 
commences. It does not follow, however, that 
the subsequent development of an organism which 
falls from the standard of its race, is without com- 
plexity. As a matter of fact, a glance at the 
anatomy of a flea very conclusively shows how 
intricate and complex its evolution has been 
while on its downward path. With the loss 
of its wings a marvellous development of 
POS < lace: i Ss are 
iain be aie ie eal, RBS the legs has taken place ; indeed, fleas ar 
THE JUMPING LEG OF A FLEA. the greatest jumpers known in nature—although 
Notice the strongly-developed muscles of the thigh. the locusts run them closely in this direction. 
The human flea has developed the jumping habit to a greater perfection than some of the 
species which are found on the lower animals. If a man of about six feet in height was as expert 
in jumping as the human flea, he would cover a mile in four springs and would reach an altitude 
of nearly two hundred feet each 
leap. 
The hedgehog is an animal 
which is very abundantly supplied 
with parasites, and amongst these 
it possesses its own particular flea. 
I was somewhat surprised a short 
time ago to discover that the 
hedgehog flea when placed on the 
ground rarely attempts to jump, 
although it is provided with power- 
ful jumping legs. The explanation 
of this curious characteristic is, I 
think, associated with the habits of 
the flea’s host. The hedgehog 
usually has a regular track to his 
hiding-place, and ground freshly 
dug will show the track even the 
next morning, for the feet of the 
* Pho } Tard, FES. : 
gece Ce eee hedgehog quickly flatten down the 
THE FEMALE HUMAN FLEA. : 
She can be distinguished from her mate by the downward curve of the soil where it runs. Consequently, 
hinder segments of her body. when the hedgehog flea loses its 
