HISTOLYSIS OF FAT-BODY OF APIS 579 



The material when fixed was sht sagittally, and sections of 

 one half the body cut transversely, 3 or 4 mm. thick. These 

 were carried up to 85 per cent alcohol by means of an apparatus 

 designed to produce a very gradual dehydration without shrinkage 

 (Bishop, 17). The pieces of tissue were then cleared in redistilled 

 anilin oil, passed through xylol and paraffin, changes being made 

 by small degrees, and infiltrated for two to four hours at 56 to 

 58°. Sections were cut 4 to 10 n. The standard fixative used 

 was Allen's B15 formula, with or without urea, although prep- 

 arations were made with picro-formol, formol-acetic, Flemming's, 

 Gilson's, hot water, etc. The stains used most successfully 

 were Heidenhain's iron alum haematoxylin, safranin-gentian 

 violet mordanted with Gram's solution, and Delafield's haema- 

 toxylin, for chromatic structures; polychrome methylene blue 

 proved a very delicate stain for the nuclear membrane; for 

 cytoplasmic structures, the albuminoid globules, etc., eosin, 

 aurantia, acid fuchsin, licht griin, orange G, and Congo red. 

 Eosin and aurantia gave good differentiation of the globules. Fat 

 was stained with sudan III and osmic acid. An old much-used 

 bottle of Mallory's phosphottmgstic haematoxylin, diluted with 

 equal parts of distilled water, gave beautiful preparations showing 

 all structures, nuclear, cytoplasmic, and nuclear membrane, 

 but stained so generally that it masked all counterstains used for 

 qualitative differentiation in cytoplasmic structures, such as the 

 albuminoid globules. 



c. Microscopic anatomy. The first stage to which close study 

 has been directed is that designated B, in which the fat-cells, 

 or trophocytes, having ceased to divide, are laying up appreciable 

 stores of globular fat. Before this stage, during what may be 

 designated rather loosely as a multiplication period, this tissue 

 is characterized rather by the irregular shape of the cells than 

 by their visible fat-content. From this period forward, the de- 

 posit and the metabolism of fat appear under the microscope as 

 the most striking and characteristic activities of the tissue. An 

 analysis of text figures B to F will comprise a presentation of 

 the chief anatomical findings of this paper. 



