234 Journal of Agricultural Research voi. iv, N0.3 



reagent were extracted, just as filter paper would if treated with the 

 same solution and then an excess of the reagent washed oflf. 



The color might disappear if the washing were very prolonged, but in 

 this writer's case the washing was not thorough, because when the cover 

 glass was sealed to the slide a strip of white filter paper, brought in contact 

 with the solution, gave a bluish color, indicating presence of a reagent* 

 Moreover, as Meyer (12) has shown, a very small amount of a reagent is 

 necessary to give reliable results. Besides, treatment with a concen- 

 trated solution of iodin for 24 hours gave no trace of coloring whatever 

 to the granules. Treatment with Meissner's concentrated solution of 

 cells of the organism, kindly forwarded us by Prof. D. H. Jones, gave a 

 strong golden-brown color. ^ 



It should be observed that the trials were repeated also on old cultures 

 (14 or 15 days old), but no reaction took place. This would be contrary 

 to the statement by Jones (9) to the effect that the cells give less glycogen 

 reaction when young than when old. Also in one single slide of a com- 

 paratively young culture there ought to be many fully developed cells 

 that should react. It therefore appears natural that the granules 

 observed by the writer should be classed among those which, according 

 to Jones (9), "do not always appear to be present, do not give the 

 glycogen reaction, but do stain with various aniline dyes." ^ Their 

 failure to take the blue color with iodin excludes their starchy nature. 

 They are not fats, because treatment with ether did not dissolve them, 

 because they stained with extraordinary facility, and also because they 

 were not dissolved by treatment with glacial acetic acid. It is very 

 probable that the granules observed by Mencl (11), which stained easily 

 with methylene blue, are the same as those of Jones (9), just quoted. 



Although repeated trials were made to obtain the color differentiation 

 reported by Mencl (11) with methylene blue and glycerin, the results 

 were always unsatisfactory. The granules never stained red. 



Mencl (11) and Prazmowsky (15) class the granules as "nuclei- or 

 nucleo-equivalents," thus implying that they have a chromatic nature. 

 Jones (9) considers them as motile flagellated granules, resembling the 

 reproductive organs of many Cyanophyceae. This naturally implies 

 that they contain chromatin as a necessary constituent. Neither of 

 these authors proved his assertions with standard methods. 



The granules that were obtained by the writer stained easily and 

 deeply, but gave no reddish color with a i to 1,000 methylene-blue 

 solution, though they gave it with a i to 5,000 solution, as metachro- 

 matic granules usually do. They responded positively to all the tests 

 carried out to distinguish their metachromatic character. 



1 Since this method is not reliable, the present writer intends, in due time, to make a quantitative 

 determination of the glycogen to be found in large quantities of cells of A . ckroococcum grown under 

 conditions equal to the preceding. 



- As to the ciliated gonidia described by Jones (9), see under "Staining the organism" and "Discussion 

 of results." 



