772 THE POPULAR SCIENCE MONTHLY. 



long, slender tube for pumping the nectar of flowers. This "pro- 

 boscis " is frequently much longer than the insect's body, and when 

 not in use is beautifully coiled under the head. The humming-bird 

 has a long, slender beak for the same purpose, which in some species 

 is curved to fit certain flowers, it is said. Bees and flies lap their 

 food, the former with a hairy tongue, the latter with a proboscis 

 knobbed at the end. The sucker of the leech is furnished with three 

 little saws for cutting the skin of its prey in order to draw its blood. 

 A barbed tube is used by the louse ; while the irrepressible mosquito 

 is provided with a whole set of surgical instruments. Its proboscis, 

 which seems so simple to the unaided eye, is found to be a " flexible 

 sheath inclosing six distinct pieces, two of which are cutting-blades or 

 lancets, two notched like a saw with reverted teeth, a tubular canal, 

 and the central one an excessively acute point, which is also tubular." 



Fig. 2— Modth-Parts or Mosquito. 



It is interesting to know how the insect uses so many instruments, as 

 we have all had the pleasure of being the subjects of her surgical skill 

 (for only the female is admitted to the practice of bloodletting). 

 " When the attack is made, the gnat (or mosquito) brings the tip of 

 the organ within its sheath to press upon the skin into which it pres- 

 ently enters, the sheath remaining without and bending into an angle 

 as the lancets descend. When the weapon has penetrated to its base 

 — a distance of one sixth of an inch or more — the lancets move laterally 

 and thus cut the flesh on either side, promoting the flow of blood from 

 the superficial vessels ; at the same moment a highly irritative fluid is 

 poured into the wound, which has the effect of diluting the blood and 

 thus rendering it more capable of flowing up the slender central tube 

 into the throat of the insect." 



Many aquatic animals, especially the low, fixed forms, depend for 

 subsistence upon the minute organic particles floating in the water. 

 But if the animal can not move in search of food it must have some 

 me^ns of bringing the food to itself. This is frequently accomplished 

 by vibrating hair-like appendages, called cilia, which produce currents 



