OF DIGESTION. 383 



upon touching or pressing the creature, and is probably produced by 

 a peculiar secretion, which serves them as a defence against their 

 enemies. 



Among the Hymenoptera also many bees are distinguished by a 

 peculiar very agreeable smell, which may in many instances however 

 originate from the flowers they visit. 



One genus of this large family, the domestic bee, produces a secre- 

 tion of a distinct nature, which is not found in any other insect. This 

 secretion, which distinguishes itself less by its smell than by its peculiar 

 quality, is the wax of which the bees construct their cells. The 

 secreting organ is found in the space between the ventral plates of the 

 five intermediate abdominal segments, and exhibits itself as a delicate, 

 soft, structureless membrane which passes from the superior half of 

 each ventral segment, and, describing an arch, inserts itself in the 

 preceding; hence it is the true articulating membrane itself, which 

 has here transformed itself into a perfect secreting organ. But such 

 a function of the articulating membrane is not without analogy in other 

 insects, for in the Dytici the membrane between the head and thorax, 

 in Mdoe that between the femur and tibia, and in Coccinella that 

 between the several ventral plates, is a true secretory organ. The 

 form of the secreting surface presents itself as a long octagon, which is 

 divided into two halves by a central horny ridge. This octagon lies at 

 the anterior surface of each of the central five ventral plates, and stands 

 in connexion with the posterior side of the preceding plate, by means 

 of a process. Thus each bee has five secreting pockets in its abdomen. 

 In these pockets the wax is prepared in the form of very thin, white, 

 and very fragile plates, which are firmly attached to the secreting 

 surface, and thence removed when the bee wishes to construct a cell. 

 For this purpose it breaks the wax plates into small pieces, and by 

 means of its saliva it prepares with it a soft pappy substance, which 

 is stuck together in small pieces, and afterwards smoothed by the 

 mouth with the assistance of the saliva *. The saliva, therefore, from 

 possessing the property of dissolving the wax, must be of an alkaline 

 nature, which is proved also by its organs becoming red when laid in 

 vinegar. In the other families of the Hymenoptera, on the contrary, 

 namely, in the ants, a superfluity of acid is found in the body, which 



* See G. R. Treviranus, in the Zeitscrift fur Physiologic, vol. iii. p. 62., upon these 

 wax-preparing organs, and the mode in which the bees work it. 



