HISTOLYSIS OF FAT-BODY OF APIS 581 



faintly basophilic nuclear membrane. The amount of chromatic 

 nuclear material and the density of its staining reaction suggest 

 pronounced nuclear participation in the cell's metabolism. 

 The nucleus is as a rule pushed to one side and distorted, even 

 to the extent of being indented, by the one large fat-globule. 



This stage of the fat-cell is not limited by definite or abrupt 

 changes either at its inception or at its conclusion. The fat- 

 globule increases in diameter, at first more rapidly than the cell 

 containing it, compressing the nucleus as it enlarges. Later it 

 grows more slowly (relatively) until the nucleus relaxes to the 

 smooth oval shape of the later stage. 



Stage C. Text figure C presents a section of a larger fat-cell, 

 the difference in structure of which, from that of figure B, appears 

 to be due less to a difference of physiological functioning than to 

 mere increase in size and content. The cell comes to present an 

 appearance strikingly different from the first figure, by the mere 

 mechanical rearrangement of elements whose individual aspects 

 are precisely the same as in the former stage. The nucleus is 

 surrounded by a homogeneous mass of cytoplasm extending 

 uniformly from nuclear membrane to cell wall, except where dis- 

 placed by fat-globules. A peripheral ring of these globules, the 

 largest of which ' approximate the size of the prominent globule 

 of the former stage, and the smallest of which surpass the limits 

 of microscopic vision, displace most of the readily staining cyto- 

 plasm from among them, and give the appearance of lighter stain- 

 ing in this region. The globules are often so numerous and so 

 massed that they distort each other from the characteristic 

 spherical form. This accretion of peripheral fat continues with 

 a progressively increasing number of vacuoles, until just after the 

 sealing over of the larva and the cessation of the nutritive supply.^ 



• Some light is thrown on the mechanics of the change in fat disposal from 

 stage B to C (text figs. B and C) by a consideration of the surface: volume ratio. 

 The volume of a sphere increases as the cube of its radius; the larger the cell diame- 

 ter relative to the diameters of the contained fat-vacuoles, the larger will be the 

 radius of that portion of the cell's volume into which the non-fatty material 

 gathers centrally. For instance, one-half the volume of a sphere whose radius 

 is 1 is contained in a sphere at its center whose radius is 0.79, the other half in a 

 peripheral shell of 0.21 thickness. If, say, 50 per cent of the cell were fat, it could 



