22 ROMANCE OF THE INSECT WORLD CHAf. 



though all are subservient to the one end, the assimi- 

 lation of food into matter fitted for nutrition.* New 

 structures are likewise added of which formerly there 

 was no appearance. Taking the principal parts 

 of the tube in their order of succession from the mouth, 

 with which the digestive structures are continuous, an 

 oesophagus, or gullet, a stomach, and a small and 

 large intestine may be distinguished. Glandular 

 appendages complete the apparatus. 



Food passes from the mouth into the gullet, or 

 oesophagus,* a portion of the tube that runs through 

 the thorax in a straight line. In the case of insects 

 that live on fluids it is usually narrow, when the diet 

 is more or less solid it becomes comparatively wide 

 and strong. A dilation of the gullet, called the crop, 

 is often present, where food may be stored for a 

 time previous to digestion. This is a provision 

 common in gross feeders, such as grasshoppers and 

 locusts, and in those that provide for the wants 

 of their young. From the crop the bee disgorges its 

 gathered honey into the cells of the comb by means 

 of the muscular coats of the reservoir. A valve * cuts 

 off the membranous bag from the true stomach, and 

 must effectually prevent all regurgitation * from the 

 latter into the former. In butterflies, and occasionally 

 in flies, the crop is rather more separated from the 

 gullet, and opens into it by a tube or neck. The 

 stomach, the principal organ of digestion, varies much 

 in length and in size generally. Here the food is 

 mixed with the gastric juice, and is finally converted 

 into chyme, just as in ourselves and the higher 

 animals. As in man, the secretion depends upon the 



