12iS OBSERVATIONS ON THE 1AVK HI8TOKY, ETC. 



numbers of filaria embryo in the stomachs of the 

 mos(iuitoes, and by a series of observations showed that, 

 thouf^^h many of them were digested, others pierced the stomach 

 and lodged in the muscles of the mosquitoes. The embryo go 

 through the changes that fit them for an independent existence, 

 and the mosquito dying, the filaria escapes into the water, which 

 may be drunk by human beings and so propagate the disease. 

 Dr. Thos. Bancroft, who has recently devoted a good deal of at- 

 tention to this subject, has, apparently, shown that the disease is 

 not propagated in this way, as the young filaria are killed by a 

 few hours immersion in water. 



One peculiarity of the mosquito is its music, if we are dis- 

 posed to dignify such a sound by that name. These sounds are 

 caused by the rapid vibration of parts of the body. The wings 

 help to make it by their rapid motion. But the main cause is 

 the breathing apparatus. You remember the breathing tubes of 

 the larvce. A similar arrangement of tubes exists in the adult 

 mosquito. These tubes terminate in round holes on the sides of 

 the body. Air is admitted and expelled through these openings 

 or stii/vKitd. Just below their margins are two folded leaflets 

 which vibrate beneath two external valves by the movement of 

 the air. They resemble two reeds in a pipe. The air passing 

 rapidly through these openings during flight, they, being capable 

 of contraction or expansion at the will of the insect, is the main 

 cause of the sound. 



The next time you entertain a mosquito listen to the song. 

 As she slows her movement over your head the note will grow 

 deeper on account of the slow movement she is executing. The 

 male mosquito has a voice, and sings too. But his voice is just 

 the opposite of that which exists in the human family. The 

 female has the deep booming voice, while the gentleman's is 

 pitched on a much higher key. It is weaker and much more 

 shrill than that of the female, and the tones likewise differ in 

 different species of mosquito. 



Now the question arises — "What is the use of the mosquito ? 

 Does it exist only for torment ? "Well, I do not think we 

 understand all the uses of the insect world sufficient to give a 

 decided answer to that question. Our knowledge must be much 

 more extensive and complete before we conclude that they are 

 merely nuisances. 



