1902.J NATURAL SCIENCES OF PHILADELPHIA. 331 



because upou its answer depends, largely, the physiological inter- 

 pretation of the facts here presented. 



In the first place, it should be said that the choice of iron- 

 hsematoxylin stain for the study of fat absorption was for the sake 

 of very decided advantages from the morphological standpoint. 

 The demonstration of the alveolar structure of the cytoplasm, for 

 example, is much more satisfactory with this stain than with any 

 other I have used. Fat globules may be quite clearly distinguished 

 from other granules, black after osmic acid and iron-hsematoxy- 

 lin, by merely destaining to a considerable degree with the 1 per 

 cent, iron-alum solution. Blackened deeply by osmic acid, they 

 retain their color after other granules blackened only by the stain 



Fig. 19.— Sections of two cells X 600 from median portion, "mid- 

 gut" oi Porcellio scaber, fed with beef suet ; intestine fixed after 115 his. 

 in Flemraing's fluid. Bl.cg., blood coagulum ; Bm., basement mem- 

 brane ; Leuc, leucocytes containing fat. All black globules outside the 

 nucleus are fat. 



lose the color. This is the case in fig. 18 ; the black color in the fat 

 granules is due solely to the osmic reaction. 



Secondly, with acid fuchsine stain it is an easy matter to dis- 

 tinguish granules from fat globules. In fig. 10, Plate XVI, they 

 are shown retaining the osmic color, while all the other cell parts 

 are red. The nuclei which are not shown in these two cells were 

 also red. Figs. 17 and 19 likewise are from sections stained in 

 acid fuchsine ; the fat globules were all black, the nuclei red. It 

 has been seen (p. 315) that albuniose granules take the acid fuchsine 

 in aniline water even after an osmic fixation. It is consequently 

 easy also to distinguish the fat globules from albumose granules. 

 The food was pure fat or fat and carbohydrates mainly, and sec- 

 tions treated in the same manner as those in which albuniose was 



