LESSON 42.] NUTRITION IN INSECTS. 149 



the sac, the tube in connecting with it becomes exhausted, and as 

 the other extremity has been previously made air-tight, the as- 

 cent of fluid, as a sudden jerk, is inevitable. Of course its tendency 

 is to rush into the pumping stomach, and if this could be achieved, 

 death would most likely be the immediate result, as much as if a 

 pail of water were suddenly poured into our lungs ; but long before 

 the air can reach the pumping stomach, reaction takes place, and 

 the fluid is driven through a very short tube, nearly at right angles, 

 but somewhat inclined to the oesophagus, into the crop, in whose cal- 

 lous margin a valve is placed to prevent regurgitation. Once in this 

 organ, the food macerates in the saliva, and becomes subject to the 

 action of its powerful muscles; in due time, it passes through a 

 valve at the lower portion, and enters the stomach (f). 



666. This latter is a very long, slender, tortuous, and convo- 

 luted tube, having (according to some authors) three distinct 

 divisions in its interior ; it terminates by a pylorus just before the 

 commencement of the ileum (</), into which intestine the biliary 

 ducts, as usual^ enter. The liver (&, h) is of great size, and like the 

 same organ in the Caterpillar, appears to be filled with oil cells, 

 exceedingly minute, however. The ileum, too, is of unusual extent, 

 but at length terminates in the Colon (i). 



667. Thus, as briefly as circumstances would permit, the chief, 

 and most remarkable characteristics of the nutrimental organs, and 

 the adapting forms of the mouth in the Linnsean orders of insects 

 have been described. It is unnecessary to speak of the Aptera, in- 

 asmuch as they really belong to the other orders, the want of wings 

 being a sexual distinction ; moreover, the majority of the individuals 

 of this order were not Insects at all, and have been removed to the 

 Classes to which they properly belong. 



668. The structure of the nutrimental organs of insects is parti- 

 cularly interesting from the fact of their close agreement with like 

 structure in the Vertebrate animals. Thus, the ccecal appendages 

 around the pylorus of the Cockroach, bear close resemblance to a 

 similar structure found in many Fishes; in the latter they are sup- 

 posed to be salivary or pancreatic (pancreas, the sweetbread) in their 

 secretion, and this is, at least, equally probable with the Insect. 

 Feeding indiscriminately as the Blattaria do on whatever comes in 

 their way, upon flesh, or fruits, vegetables, linen, clothes of all kinds, 

 printed books and written manuscript, engravings or water-color 

 paintings, old boots and shoes, and not unfrequently nibbling the 

 toes (in hot climates) of persons while asleep, their power of digestion 

 had need be very perfect to get quit of such heterogeneous matter. 



