Sidney Klein ; 323 
To demonstrate prozymogen as basal filaments or as a diffuse chromo- 
phile substance in the base of the cell toluidene blue was employed in 
saturated aqueous solution. Better results, however, were obtained by 
a method devised by Bensley of staining in toluidene blue, orange G, and 
acid rubin. This method is as follows: the sections cut as thin as possible 
in paraffin and fastened to the slide by the water method are passed 
through benzole, absolute alcohol, and graded alcohols, to water. They are 
then stained for a period of one minute with a mixture containing equal 
parts of the saturated aqueous solutions of Orange G, and acid rubin. 
Then wash in water and stain for one minute in saturated aqueous solu- 
tion of toluidene blue. Wash in water; transfer to absolute alcohol; 
clear in benzole, and mount in balsam. The result as far as the distri- 
bution of the toluidene blue is concerned is much the same as that ob- 
tained by staining with this dye alone. The intensity of the blue stain, 
however, is much increased, and in addition the method offers the ad- 
vantage of the contrast stain produced by the rubin and orange. By this 
method chromatin and prozymogen (or basal filaments) are stained 
intensely blue, protoplasm faint bluish, zymogen granules red, and the 
contents of goblet cells remain unstained. 
Confirmatory evidence of the presence of prozymogen in the Paneth 
cells was sought by means of the microchemical reaction for organic iron 
introduced by Macallum. 
In the guinea pig Paneth cells are very abundant in the glands of 
Lieberkiihn of the small intestine. They occupy chiefly the deep ends 
of the gland where they often form a continuous layer which is inter- 
rupted by comparatively few goblet cells. A few also occur on the sides 
of the gland but the upper ends of the glands are wholly free from them. 
The structure of these cells depends on the stage of physological 
activity. In the animals which are kept constantly supplied with food 
of which they are allowed to partake at will, the cells are cylindrical in 
shape, the outer end being somewhat broader than that which is directed 
towards the lumen. In each cell two zones of about equal width are 
easily recognized. The distal zone directed towards the lumen of the 
gland is occupied by fine granules which are so closely crowded that it 
is often difficult to recognize the thin laminae of cell-protoplasm which 
separate them from one another. In material fixed in aqueous sublimate, 
however, many cells may be found from which the granules have been 
removed and here we find the distal zone occupied by a fine meshwork 
which corresponds in the size of its spaces to that of the granules, indi- 
cating that each granule occupies a small space in the protoplasm, a thin 
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