370 R. R. BENSLET. 



by the glands of animals that have been in active digestion for 

 ten to twelve hours, and therefore exhibit a well-marked outer 

 protoplasmic zone (fig. 3). In sections from such glands, 

 stained in freshly prepared Mayer's hsemalura, a pure nuclear 

 stain is obtained in all the cells, with the exception of the 

 chief cells of the body of the gland, the outer protoplasmic 

 zone of which also stains blue. A more vigorous stain of this 

 portion of the cell may be obtained by the use of Ehrlich's 

 acid haematoxylin, diluted for use with a 5 per cent, solution 

 of ammonia alum in water. The sections, after staining in 

 this fluid, are washed in tap water, then dehydrated and mounted 

 by the usual methods. Staining in very dilute solutions of 

 methylene blue, gentian violet, or safranin, followed by 

 rapid dehydration in absolute alcohol, and clearing in benzole, 

 also gives a very serviceable stain of the outer zone of the 

 cell. In sections so stained the outer zone of the cell 

 exhibits an obscurely fibrillated structure, which reminds one 

 strongly at first of the striated epithelial cells in the intra- 

 lobular ducts of the salivary glands (fig. 3). On closer exami- 

 nation it may be seen that the fibrillation in the outer zone of 

 the chief cell is not so regular, nor are the fibrillse so distinct 

 from one another as in the salivary ducts. 



The strong affinity for nuclear stains exhibited by the outer 

 protoplasmic zone of the chief cell is due to the presence in it 

 of a chromatin or firm organic compound of iron, the prozy- 

 mogen of Macallum, as may be shown by the reactions for the 

 presence of iron. If a section of a piece of mucous membrane 

 that has been hardened in absolute alcohol be treated with 

 ammonium hydrosulphide, or an acid solution of potassium 

 ferrocyanide, no reaction occurs, indicating that no inorganic 

 iron is present in the cell. If, however, the sections be first 

 treated with a solution of pure sulphuric acid in alcohol, con- 

 taining four volumes per cent, of the former, for a period of 

 three to six hours at a temperature of 37° C, and then, after 

 thorough washing in fresh alcohol, transferred to ammonium 

 hydrosulphide or acid ferrocyanide solution, a strong reaction 

 for iron is obtained, not only in the chromatin of the nucleus. 



