1892.] MICROSCOPICAL JOURNAL. 281 



The hituler portion of the abdomen is different in the two sexes 

 of grasshoppers. In the male the 9th and i ith sterna are Large and 

 curve upward, while the corresponding terga are very small and 

 followed by a few small movable pieces, among which is located 

 the vent and the opening of the genital gland. In the female the 9th 

 and loth sterna are represented by a portion which projects down 

 and back ; the terga are as in the male, but they bear parts which 

 extend backward and upward. These diverging parts are used 

 in boring holes in the earth to deposit the eggs, which pass out 

 between them. The abdominal somites bear no limbs. 



Internal Anatomy.* 



The parts within an animal's body form sets of organs called 

 systems. Some of these are so soft and delicate that they require 

 to be held in place by stronger matter which forms the skeleton. 



In the grasshopper the skeleton is a shell composed of matter 

 resembling horn, called chitine., which contains the soft living 

 organs. Since this shell fits closely over tlie living organs in 

 many of their parts we can learn a good deal about the animal by 

 studying the external anatomy. But to have any adequate idea of 

 the inner structure we must cut below the shell and explore among 

 the parts within it. The parts of the body are called oi-gans., 

 each organ having a particular use or function ; the various func- 

 tions are of only a few kinds, and all the organs performing one 

 general kind of function are called a system. 



I. The alime.jitary system (Fig. 5) is com posed of organs whose 

 collective functions are to receive food and convert it into blood. 

 It is a continuous tube, open only at the mouth and a?ius., whose 

 cavity is entirely distinct from the cavity of the body, where the 

 internal organs lie. It is divided into more or less separate cham- 

 bers and receives ducts or passages from other alimentary organs 

 which open into it. The mouth is the first organ of the system ; 

 it is furnished with lips and jaws, mandibles and maxillae, which 

 chew the food. Into the mouth cavity a tube opens from the 

 salivary glands of each side which, lying chiefly in the thorax, 

 secrete the blackish saliva. The mouth cavity continues upward 

 as the throat and passes with a bend into the crop., which is an 

 enlargement of the tube partially filling the cavity of the thorax ; 

 this receives the food and passes it back into the next organ, the 

 stomach., which occupies the first four abdominal somites. Sur- 

 rounding the hinder end of the crop are 8 blind pouches, called 

 gastric cceca., which open into the crop. The stomach opens 

 into a narrower tubular organ, the ileum., and this at its junction 

 with the stomach receives a number of urinary tubes, t?ialpighian 

 tubes ; the alimentary tube continues back as the colon and rectum 



*The more important points in the internal an:Uomy can be readily demonstrated by 

 opening a specimen along the back under water, the specimen being pinned down upon a 

 layer of wax in the bottom of a pan The organ should be gently separated with teasing 

 needles. 



