PLATE 22. 



Fig. 7. Oscillatoria margaritifera. Longitudinal section. K. I. Ehr. Haem. 

 a represents a resting cell, b the beginning of cell division, c a cell 

 almost divided, and d a recently divided cell. 



Fig. 8. Oscillatoria chalybea. Longitudinal section. K. I. Ehr. Haem. 

 This was stained longer than the preceding in order to bring out the 

 a granules in the nucleus. The unstained quadrangular bodies have 

 not been identified. 



Fig. 9. Oscillatoria brevis var. Longitudinal section. K. I. Ehr. Haem. 



Fig. 10. Oscillatoria Oleni. Longitudinal section. K. I. Ehr. Haem., 

 counterstained with wasserblau. The cells are slightly shrunken and 

 pulled apart, leaving the dividing nucleus in the sinus. The nucleus 

 occupies nearly the entire length of the cell, and the chromatin has a 

 tendency to arrange itself in the longitudinal direction of the fila- 

 ment. 



Fig. 11. Cylindrospermum UcJieniforme. Longitudinal section. Living 

 material stained with Ziel's carbol fuchsin ; and counterstained with 

 methylene blue. The first stain colors the cytoplasm and the chro- 

 matin red, and these are changed to blue by the second stain, which 

 also stains the granules red. The two cells are slightly pulled apart, 

 showing a strand of chromatin still undivided between the nearly 

 divided cells. 



L288J 



