H2 SCIENCE FROM AN EASY CHAIR 



the toes, in others upon the legs, at the side or back of 

 the head (the elephant), in the middle of the back or 

 about the tail. The fluid secreted by these glands is not 

 poisonous nor acrid, but odoriferous, and seems to serve 

 to attract the individuals of a species to one another. 

 They resemble in structure and often in position the 

 poison-glands of the spurs of the duck-mole and spiny 

 ant-eater. 



Many insects produce a good deal of irritation, and 

 even dangerous sores, by biting and burrowing in the 

 human skin, without secreting any active poison. Often 

 they introduce microscopic germs of disease in this way 

 from one animal to another, as, for instance, do gnats, 

 tsetze-flies, and horse-flies, and as do some small kinds of 

 tics. The bites of the flea, of midges, gnats, and bugs are 

 comparatively harmless unless germs of disease are intro- 

 duced by them, an occurrence which, though exceptional, 

 is yet a great and terrible danger. We now know that 

 it is in this way, and this way only, that malaria or ague, 

 yellow fever, plague, sleeping-sickness, and some other 

 diseases are carried from infected to healthy men. Various 

 diseases of horses and cattle are propagated in the same 

 way. The mere bites of insects may be treated with an 

 application of carbolic acid dissolved in camphor. The 

 pain caused by the acid stings of bees, wasps, ants, and 

 nettles can be alleviated by dabbing the wound with weak 

 ammonia (hartshorn). Insects which bury themselves in 

 the skin, such as the jigger-flea of the West Indies and 

 tropical Africa, should be dug out with a needle or fine 

 blade. The minute creature, like a cheese-mite, which 

 burrows and breeds in the skin of man and causes the 

 affliction known as the itch must be poisoned by sulphur- 

 ous acid a result achieved by rubbing the skin freely 

 with sulphur ointment on two or three successive days. 

 A serious pest in the summer in many parts of England 



