LESSON 39.] 



NUTRITION IN INSECTS. 



139 



FIG. 229 



Proventriculus of Gryllotalpa. 



sected from the Mole cricket (Gryllotalpa) from Jamaica, a much 

 smaller insect than the European species, but fearfully destructive. 

 The specimen and its 

 companions cost the 

 proprietor of a farm 

 there upwards of 60,- 

 000 sterling, $300,000, 

 by the entire destruc- 

 tion of his crop of sugar 

 cane. 



Interiorly the giz- 

 zard is divided into 

 six compartments, by 

 means of six bones (a, 

 a), which occupy the 

 whole longitudinal length of the organ. Between every two of the 

 bones are three rows of teeth, and of these, the teeth in the centre, 

 or the central row, are the largest and most powerful. Outside of 

 the large teeth are two rows, one on each side of them, and still more 

 outside are other two rows. All the teeth in these several rows 

 differ somewhat in their structure ; in addition to these, there are 

 large teeth above and below the rows, and to assist their action the 

 external surface is covered with a muscular coat of extraordinary 

 power. The entire number of teeth contained in this gizzard is two 

 hundred and twenty-two. So great is their capability for tearing 

 and minutely dividing every substance presented to their action, that 

 they have been compared, most fitly, to the . machine used in cloth- 

 making, called " the Devil," for nothing can resist its action. 



A still more enlarged view is given of the position of the bones 

 (a, Fig. 230), and of one row 

 of the teeth. The lateral 

 teeth, described above, are 

 here lettered 5 / the* central 

 row, including a large middle Enlarged view of one row of the teeth, Gryllotalpa. 



and two lateral teeth, are marked c and d. 



627. In the intestinal canal of man, and the higher animals, a 

 vast assemblage of glands, of minute size and uncertain function, are 

 found, some of them solitary, others aggregated. Their presence ap- 

 pears to be essential to the action of this' portion of the canal. 



628. The Ileum of the house-cricket (Acheta domestic) exhibits 

 a wonderful development of similar glands. This intestine is dis- 



FIG. 230. 



