8 Descriptive Zoology. 



Absorption in the Grasshopper. The absorbed food ma- 

 terials from the digestive tube pass directly into the general 

 blood of the body cavity, there being no special set of 

 tubes as in man and vertebrates generally. 



The Excretory System of the Grasshopper. The urinary 

 tubes (formerly called the malpighian tubes) extend into 

 the blood of the body cavity and extract from it essen- 

 tially the same materials as the kidneys of the higher 

 animals do. As above stated, these tubes empty into the 

 intestine. 



The Nervous System of the Grasshopper. The nervous 

 system of the grasshopper is essentially like that of the 

 crayfish (Fig. 49), consisting of a row of ganglions con- 

 nected by a nerve cord lying along the floor of the body 

 cavity. It really is composed of two rows of ganglions, 

 each connected by its own chainlike cord ; but usually 

 the two corresponding ganglions unite, forming what seems 

 a single ganglion. In the grasshopper, the nerve cord is 

 plainly double throughout the head and thorax, while in 

 the abdomen the cord appears single. There are ten gang- 

 lions, two belonging to the head, three in the thorax, and 

 five in the abdomen. The first ganglion, often called the 

 brain, is above, or rather in front, of the gullet. From this 

 the two strands of the nerve cord pass to right and left of 

 the gullet and again unite in the second, or infra-esophageal 

 ganglion, forming the nerve ring (" nerve collar ") found in 

 arthropods and mollusks. 



The Senses of the Grasshopper. It is very evident that 

 the grasshopper can see and hear, and it does not require 

 extended experiment to show that it has also the sense of 

 touch. The large compound eyes, composed of many 

 facets, give a wide range of vision ; but the sense of sight 



