334 PROCEEDINGS OF THE ACADEMY OF [May, 



chromic acid, etc.); (c) they slain densely black after all osmic 

 fixations; (d) they retain this color after staining with acid -fuchsine 

 in aniline water, and are thus distinguished from albumose gran- 

 ules; (e) they retain the black color after iron-hjematoxylin and 

 deslaining with iron-alum, and are tha? distinguished from chroma- 

 tin granules, so that the granules inside the nucleus, which phj^sically 

 very much resemble the blackened granules in such preparations, 

 are never oily in nature — in other words, the fat does not penetrate 

 into the nucleus in appreciable quantities; (/) the insolubility of 

 these granules in xylol and ether cannot be taken as an indication 

 that they are not composed in part at least of fat, for, as Altmann 

 observes, the solubility depends on the purity of the fat. Finally, 

 the insolubility of globules in such cases may be due to admixture 

 with some albuminous fluid which precipitates in the formation of 

 the globule and constitutes its insoluble portion. 



Granting now that the globules found in the absorbing cells after 

 feeding with pure fats are really fatty in nature, it may be inquired 

 how they came there, whether they are absorbed as such or whether 

 they were synthesized from chemical products of digestion. In 

 short, for which theory of fat absorption — the emulsion or the solu- 

 tion theory — do the facts speak ? Without going into a history 

 of this controverted question here, it may be pointed out, by way of 

 introduction to the interpretation of what follows, that the morpho- 

 logical evidence is scarcely crucial evidence in point. For, on the 

 one hand, it is claimed by the adherents of the solution theory that 

 if fat globules are not demonstrable in the luminal border of the 

 cell, but only after a portion of the cell has been traversed, then 

 fat did not enter the cell as such, but has been synthesized some- 

 where in its course since entering. The emulsionists, on the other 

 hand, say it is just as reasonable to suppose that the emulsion parti- 

 cles are so small that at the time they enter the cell they cannot be 

 seen with the highest powers of the microscope, and become visible 

 only when a number of them have fused together, as they 

 plainly do. 



The isopod, because of its small size, is not favorable for a 

 chemical study of digestion. Consequently I have not attempted to 

 supplement the morphological study by that means. Nevertheless, 

 it seems worth while pointing out that the appearance here pre- 

 sented is all that is required by the solution ists for morphologica 



