232 Journal of Agricultural Research voi.iv. N0.3 



Glycogen. — Smears were mounted in a saturated aqueous solution of 

 iodin, sealed with paraffin, and observed at once or 24 hours later. 



Meissner's solution instead of iodin was also used. 



A. Meyer (12) also suggests boiling for three minutes in a weak solu- 

 tion of sulphuric acid (2 drops of concentrated HjSO^ in 5 c. c. of HjO). 

 Glycogen is dissolved by this treatment. 



The granules did not give any golden color with iodin solution, even 

 after 24 hours, contact. Meissner's solution, not removed from cells, 

 gave a very dark golden-yellow color. To be certain, however, of the 

 presence of glycogen in the cells, this golden color should persist after 

 the excess of Meissner's solution has been replaced by water by means of 

 capillarity. The preparations of the writer, nevertheless, did not retain 

 the golden coloration after capillary washing of the mount, although a 

 strip of filter paper placed on the edge of the cover glass in contact with 

 the wash solution took on a faint-blue color. 



The granules were dissolved by the treatment with sulphuric acid. 

 It is to be remembered that also metachromatin is dissolved by boiling 

 in water for three to five minutes. If the sulphuric acid in the cold 

 were not to dissolve the latter, perhaps it would at the boiling tem- 

 perature. Moreover, the sulphuric-acid solution used for testing the 

 solubility of metachromatin is 1.2 to 1.3 times stronger than the one 

 used for the detection of glycogen by this method, which would probably 

 account for the solution of the granules. The granules in this case, 

 according to my view, are not of a glycogenous nature. 



The mounting of smears in a dilute Meissner solution (2 drops in 5 c. c. 

 of HjO) showed the cells stained in a homogenous manner straw-yellow, 

 while the mounting of a smear of a blastomycete {Sdccharomyces cerevi- 

 tiae) in the same solution gave a decided golden-brown granulation. 



Metachromatic and chromatic granules. — To distinguish between 

 the two kinds of granules, several tests were used. 



(a) The ruby-red color, which should be developed by the Roman- 

 owsky-compound method, indicates chromatin. Protozoa are a good 

 example of the results to be obtained. 



In the large number of slides prepared no ruby color was developed by 

 the Romanowsky stain. 



(&) A cover-glass preparation was stained with methylene blue, i to 11. 

 After washing in water treated with i per cent of sulphuric acid, chroma- 

 tin should discolor at once, while metachromatin should not. 



Treatment with the sulphuric- acid solution did not decolorize the 

 granules, but it decolorized the cell network. 



(c) A cover-glass preparation stained with methylene blue was treated 

 with a 5 per cent solution of sodium carbonate. Chromatin should 

 remain colored ; metachromatin should discolor. 



