140 



ANIMAL PHYSIOLOGY. 



[LESSON 39. 



played in Fig. 231, where the glands are aggregated. A more highly 

 magnified view of two of these glands is given in Fig. 232. 



FIG. 231. 



FIG 



Iliac glnnds of Cricket. 



Ileum of the House Cricket. 



Fig. 233. 



629. There appears to be great similitude between the perform- 

 ance of nutrition in the vegetable feeding insects and the vegetable 

 feeding ruminant quadruped. In both there are four distinct sacs, 

 devoted to this function ; in the insect, mastication is effectively per- 

 formed by the wonderful gizzard ; in the Ox, by the peculiarly con- 

 structed teeth. Saliva is abundant in both, and each possesses a 

 magnificent display of aggregated iliac glands. 



630. The food that is intractable, and yields its nutriment with 

 difficulty to the herbivorous quadruped, is no less difficult and in- 

 tractable to the vegetating insect, and both require an extraordinary 

 adaptation of many organs to reduce it to subjection. 



631. The next order, the Lepidoptera, presents an equally singu- 



lar structure of its mouth ; here the 

 upper lip and the upper jaws are so 

 minute as almost to elude detection. 

 Of the three triangular plates pre- 

 sented at the upper part of the figure 

 (Fig. 233, a), the central portion is 

 the upper lip, and the upper jaws are 

 of the same size nearly, and shape, on 

 either side of it. 



632. The Butterflies and Moths 

 rarely feed at all ; but when they do 

 condescend to perpetrate such vulgari- 

 ty, they manifest great indifference, 

 hovering over a flower, still on the 

 wing. At last, probably, (hey incline to take a mere sip of the 

 delicious fluid found in the nectary, and for this purpose unfold, and 

 make straight, their spirally wound under jaws (5), which, in some 



Mouth of Cynthia cardui (painted lady) 

 Butterfly. 



