54 STUDIES OF ANIMAL TYPES 



and ground up, as it were, into fine bits. Note the 

 delicate, white salivary glands, one on each side of the 

 crop. They connect with the mouth by means of two 

 salivary ducts. 



Succeeding the crop, but not distinctly separated from it, 

 is the proventriculus, or gizzard. Like that of a chicken, 

 the locust's gizzard has thick, muscular walls for com- 

 minuting the food. At the posterior end of the gizzard 

 there is a circle of rather large, conspicuous appendages, 

 the gastric cceca. Note their shape, number, and manner of 

 attachment to the alimentary canal. Their function is to 

 secrete a digestive fluid. 



Succeeding the gizzard is the stomach, or ventriculus. It 

 is not sharply differentiated from the other parts of the ali- 

 mentary canal adjacent to it. Several long slender tubules 

 arise from the posterior end of the stomach and float free 

 in the body cavity. These are the Malpighian vessels (page 

 163 of the text). They take up impurities from the blood 

 and carry them off through the intestine. Their action is 

 urinary, similar to the kidneys of the higher animals. 



The remainder of the alimentary canal is the intestine. 



Make a drawing of the alimentary canal showing all the 

 parts spoken of above. 



Trace the course of the food from the time it enters the 

 mouth, and show how it is acted on in the different organs 

 of the digestive system. After the food leaves the stomach 

 its nutritive portion is absorbed directly through the walls 

 of the intestine by the blood, which carries it to all parts of 

 the body. 



Remove the alimentary canal. 



Note a double, white cord running along the floor of the 

 body cavity. Note that these two threads are connected 



