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



cell. From Prazmowsky's work (15) nothing can be decided with regard 

 to this point. This author does not give much importance to it, and his 

 drawings show the same thing as those of Mencl. 



Might not a regularity in the setting of the granules, not determined 

 by the above-named authors because of unappropriate staining methods, 

 be presented at some time during the life of the cell ? 



To determine this point it is necessary to know just what are the 

 changes which the cells of A. chroococcum undergo with age. These 

 queries will have to be solved in the following order : 



(I) What are the changes in the cytology of A. chroococcum at different 

 ages of the same cell? 



(II) What is the relation of the changes in cytology to the fate of 

 the granules of the cell ? 



Since difficulties in operative technique make the solution of Question I 

 impossible/ its wording must be changed to the following: (I) What 

 are the cytological changes undergone with age by the cells of A. chroo- 

 coccum? Plate XXXI, figures 6 and 7, gives a graphical solution to 

 this question. A few words must be said about the stadia which were 

 found in the life cycle of the organized units. 



That the reticulated structure found in the cells in the writer's tests 

 was not due to the drying before fixing or to the fixing is proved by the 

 fact that many observations of vital-stained preparations made in this 

 laboratory and also by other authors showed the same structures as 

 did the treated cells. Moreover, the different methods of fixing used, 

 osmic-acid fumes, methyl alcohol, and flame — i. e., gas, liquid, and 

 heat — all gave the same structures. Therefore these structures can 

 not in any degree whatsoever be considered as artifacts produced by the 

 fixing agents. 



The first stadia were found with undifferentiated cytoplasm and 

 metachromatic granules (PI. XXXI, fig. 6, No. i ; fig. 7, No. 1,2,3). 



Second, a stadium of cytoplasmic differentration or reticulation was 

 found in v/hich the cytoplasma contracts toward the sides of the cell, 

 leaving some strands to connect the accumulations of cytoplasma placed 

 in different places of the periphery (PI. XXXI, fig. 6, No. 2-10; fig. 7, 

 No. 4-7). 



Third, a division stage was found, in which the cells after elongation 

 and differentiation in peripherical and transversal cytoplasma divide 

 and form a wall between the resulting daughter cells. The second and 

 last stadia are interdependent. 



Such a succession of stadia would then be in conformity with the one 

 resulting from the studies on Bacillus anthracis by Penau (14). The 

 nuclear phase was not found in the organisms in the experiments of the 



' vital staining, although very valuable in following cell division, could hardly give here results to answer 

 the question. Prazmowsky's (15) and Mend's (11) interpretations show the disadvantages of the method. 



