138 



ANIMAL PHYSIOLOGY. 



[LESSON 39. 



Fio. 228. 



LESSON XXXIX. 



NUTBITION IN INSECTS CONTINUED. 



622. The Linnaean order Hemiptera is, confessedly, an ill-ar- 

 ranged one; in addition to the Cockroaches, and other extraneous 

 insects, the Grasshoppers, Crickets, and their congeners, were ad- 

 mitted by the illustrious Swede. These have been removed by 

 modern Entomologists, but as the system here adopted is strictly 

 Linnaean, if it be necessary to speak of these insects at all, it can 

 only properly be done in legitimate connection. 



623. These insects, called now Orthoptera, from the leathery 

 structure of their wing cases, are all voracious vegetable feeders, and 

 they present by far the best developed proventriculus of any insects 

 known to us. 



624. The oesophagus in Locusta viridissima, soon terminates in 

 the crop (Fig. 228, a) ; at the lower portion this forms a kind of neck, 



filled with small teeth, which ends in the 

 proventriculus, in these insects a distinct 

 organ (b). It lies slightly imbedded at 

 its lower portion in another digestive 

 sac, which is transverse in its direction 

 (c), and to which a plexus of fine tubes 

 (h), like the biliary tubuli, are attached. 

 To this succeeds the true ventriculus 

 (stomach), which is usually narrow, 

 and of some length (d). At its lower 

 portion, beyond the pyloric valve, the 

 biliary vessels are connected (e), and the 

 intestine proper commences. This at 

 first is a dilated sac (/), which becomes 

 Bttrf*i . Loc^ta attenuated, and after a convolution ends 



viridissima. j n the Colon (g). 



625. The salivary glands in Locusta viridissima^ the house, and 

 most field Crickets, resemble those of the Cockroaches, and are dis- 

 played at i. 



626. The proventriculus is such a wonderful structure that it 

 merits a distinct notice, and a more highly magnified view to show it 

 (Fig. 229). 



The preparation from which the drawing was made, was dis- 



