120 THE ANATOMY OF THE HONEY BEE. 



fies merely that those cells first observed by Wielowiejski, who gave 

 them this name, were slightly wine-colored. 



Both the fat cells and the oenocytes of the honey bee have been 

 specially studied by Koschevnikov (1900), who gives the history of 

 the fat body as follows: In the larva it consists of gigantic lobes, the 

 cells of which are in general all alike and so closely packed in 30 

 or more layers that, in the younger stages, most of them assume 

 angular forms. Many of them are binucleate, and the protoplasm 

 is strongly vacuolated except for a small area about the nuclei. In 

 the full-grown larvae the fat cells become globular and filled with a 

 number of round granvdes, which, during the early part of the pupal 

 stage, are set free by a dissolution of the cell walls and float free in 

 the body cavity. In pupse a little older, having even but a very 

 thin chitinous covering, the adult fat body is fully formed, and yet 

 neither the disappearance of the larval granules and nuclei nor the 

 formation of new adult fat cells is to be observed. It seems that 

 the granules of the larval fat cells, set free at the beginning of 

 histolysis, are reassembled about the nuclei to form the fat cells of 

 the adult. In the very young imago the cells of the fat body are 

 very distinct, and each possesses a considerable amount of protoplasm, 

 with enormous vacuoles which press upon all sides of the nucleus. 

 In old bees the vacuolation is much reduced and may even be entirely 

 lacking, while the cells become filled with a solid granular plasma. 

 Old workers examined in the fall show the fat cells united into 

 syncytia or masses in which the cell boundaries are lost, although 

 the nuclei remain distinct. A queen does not appear to form these 

 syncytia in old age. 



The function of the fat body is still unsettled, but we do not 

 know of any reason why it should not be comparable physiologically 

 with the fat of vertebrate animals and constitute a reserve supply 

 of materials which can be used both as food and as a source of heat 

 oxidation. It has already been stated (p. 115) that insects main- 

 tain several degrees of body temperature. Some entomologists have 

 supposed that the fat body gives rise to the corpuscles of the blood, 

 others have believed it to be an excretory organ because concretions 

 of uric-acid salts are often found associated with its cells, while 

 still others have regarded it as the seat of the combustion of waste 

 products l)y the tracheal oxygen. 



The oenocytes of the bee are described by Koschevnikov (1900) as 

 enormous cells imbedded in the fat bodies. He says that those of 

 the larva persist into the pupal stage where they undergo dissolu- 

 tion and disappear, while new imaginal o'liocvtes are formed from 

 proliferations of the ectodermal epithelium. The new ones are at 



