146 ANIMAL PHYSIOLOGY. [LESSON 41. 



tion of the oesophagus. The external surface is ringed, and exten- 

 sively covered with hair. At the base of this organ are two little 

 processes (c) called little tongues (paraglossae), the use of which is 

 unknown. For its protection, it folds up. 



F 652. The structure of the nutrimental or- 



gans is very interesting (Fig. 241) ; the oeso- 

 phagus (a) dilates into a large crop (5), or 

 collecting bag, having one side of it particu- 

 larly enlarged. 



653. The pumping stomach is not devel- 

 oped in the Hymenoptera as a special organ, 

 but its function is shared with the crop. The 

 enlarged portion contains air ; by removing 

 the pressure of the muscles of the body, this 

 air becomes rarefied, and if the other extremi- 

 ty, the tongue, be made air tight, as it must 

 meiiifica. jjg wnen plunged deep into a viscid fluid, the 



tube, from the pumping stomach downward, becomes exhausted, and 

 the fluid in which the tongue is placed necessarily ascends by a jerk. 

 Then the action ceases, until the tube be exhausted again, which oc- 

 curs directly the insect takes off the pressure by a deep inspiration, 

 and so the action continues. 



654. The valvular projection of the true stomach is inserted far 

 into the crop (c) as a double tube, and must be withdrawn therefrom, 

 when the Bee desires to feed upon the honey it has gathered ; but so 

 long as they remain within the crop that organ is merely a collecting 

 bag, and retains the contents only until it can return to the hive, 

 where it is cast up, and deposited in the cells. 



655. During the period it remains in the crop, it is macerating 

 in the salivary secretion, whereby its vitality is destroyed, and the 

 probability of acetous fermentation obviated. From this moment it 

 is preserved so effectually that it cannot decompose, in any time. So 

 far as is known, honey is the only substance which, having been duly 

 prepared in the stomach of the Bee, is cast up, and forms wholesome 

 and delicious food for man. 



656. The stomach (d) is a long, muscular organ, which gradually 

 increases in size as it descends. Its lower portion is provided with 

 a pyloric valve, below which the ileum (e) commences. 



The bile ducts (g) empty their secretion at the commencement 

 of the ileum, which terminates ultimately in the colon (/). 



