84 THE ANATOMY OF THE HONEY BEE. 



VI. THE ALIMENTARY CANAL AND ITS GLANDS. 



1. THE GENERAL PHYSIOLOGY Or DIGESTION, ASSIMILATION, AND 



EXCRETION. 



It is no exaggeration to say that eating is the most important thing 

 that any animal does and that its alimentary canal is the most im- 

 portant organ it possesses. The entire system suffers when there is a 

 deficiency in the food supply or an impairment in the digestive appa- 

 ratus. Every other function is either subservient to or dependent 

 upon that which furnishes nourishment to the cells. The senses of 

 sight, smell, and taste are all more or less concerned in the acquisition 

 of food. The muscular system enables the animal to hunt for it, to 

 dig for it, to climb for it, or to chase living prey either on the ground, 

 in the water, or in the air, and to kill, tear, and chew it when ob- 

 tained. The blood is the servant of the stomach, for its entire func- 

 tion in insects is to carry the products of digestion to the body cells. 

 The heart furnishes the motor power of the blood. The respiratory 

 function is accessory to that of digestion, inasmuch as it furnishes the 

 oxygen which unites with the waste materials ejected from the cells 

 and renders them capable of being removed fcem the blood. This 

 removal is accomplished partly by the respiratory system itself and 

 partly by special excretory organs. Thus %e see that the sense organs 

 and the muscular system are the agents that cooperate in obtaining 

 the raw food, the digestive tract is the kitchen of the body in which 

 the food is prepared for use, the blood is the waiter that distributes 

 it, while the respiratory and excretory systems are the refuse gath- 

 erers that remove waste products. The nervous system holds the con- 

 trolling power over all these organs. It regulates them in the per- 

 formance of their duties and coordinates their actions so that they 

 all work together. It makes a unified organism out of what would 

 otherwise be simply a complex mass of" variously specialized cells. 



The reproductive function alone contributes nothing to the indi- 

 vidual. In fact, the production of spermatozoa by the male and of 

 eggs by the female and the nourishing of the embryo and the young 

 create a demand upon all the other organs for material whjch is 

 separated from the individual that produces it. But this is what the 

 organism exists for; this is its reason for being. At least this is 

 what it amounts to in the case of the individual, though from a wider 

 philosophical standpoint the real truth is probably just the reverse, 

 viz, any species exists because its individuals reproduce themselves. 



The writer has already made frequent use of the word " cell," 

 assuming that the reader is familiar with the meaning of this word 

 as used in anatomy and physiology. The entire body of an animal 

 or plant is made up of cells or their products. The word, however, is 

 misleading, for a cell is not a small sac or empty space, as was at 



