MANUAL OF THE APIARY. 57 



The number of muscles is astounding. Lyonnet counted 

 over 3,000 in a single caterpillar, nearly eight times as many 

 as are found in the human body. The strength, too, of in- 

 sects is prodigious. There must be quality in muscles, for 

 muscles as large as those of the elephant, and as strong as 

 those of the flea, would not need the fulcrum which the old 

 philosopher demanded, in order to move the world. Fleas 

 "have, been made to draw miniature cannon, chains, and even 

 wagons many hundred times heavier than themselves. 



The nerves of insects are in no wise peculiar so far as known, 

 except in position. As in our bodies, some are knotted or 

 have ganglia, and some are not. 



The main nervous cord runs along the under or ventral 

 side of the body (Fig. 8), separates near the head, and after 

 passing around the oesophagus, enlarges to form the largest of 

 the ganglia, which serves as a brain. The minute nerves ex- 

 tend everywhere, and in squeezing out the viscera of an in- 

 sect are easily visible. 



The organs of circulation in insects are quite insignificant. 

 The heart is a long tube situated along the back, and 

 receives the blood at valvular openings along its sides which 

 only permit the fluid to pass in, when by contraction it is 

 forced towards the head and emptied into the. general cavity. 

 Thus the heart only serves to keep the blood in motion. Ac- 

 cording to the best authorities, there are no special vessels to 

 carry the blood to various organs. Nor are they necessary, 

 as this nutritive fluid everywhere bathes the alimentary canal, 

 and thus easily receives nutriment, or gives waste by osmosis, 

 everywhere surrounds the tracheae or air-tubes — the insect's 

 lungs — and thus receives that most needful of all food, oxy- 

 gen, and gives the baneful carbonic acid, everywhere touches 

 the various organs, and gives and takes as the vital opera- 

 tions of the animal require. 



The blood is light colored, and almost destitute of discs or 

 corpuscles, which are so numerous in the blood of higher ani- 

 mals, and which give our blood its red color. The function 

 of these discs is to carry oxygen, and as oxygen is carried 

 everywhere through the body by the ubiquitous air-tubes of 

 insects, we see the discs are not needed. Except these semi- 

 fluid discs, which are real organs, and nourished as are other 



