2 4 



I-I/EMATOCOCCUS 



LESS. 



the fact in another and fairer way, that they travel a distance 

 equal to 2\ times their own diameter in one second. In 

 swimming the pointed end is always directed forwards and 



FIG. 3. A. Hamatococciis phivialis, motile phase. Living speci- 

 men, showing protoplasm with chromatophores (chr) and pyrenoids 

 (pyr}, cell-wall (c.u>) connected to cell-body by protoplasmic filaments, 

 and flagella fl. The scale to the left applies to Figs. A- D. 



B. Resting stage of the same, showing nucleus (mi) with nucleolus 

 ('), and thick cell-wall (c.iv) in contact with protoplasm. 



c. The same, showing division of the cell-body in the resting stage 

 into four daughter-cells. 



D. The same, showing the development of flagella and detached cell- 

 wall by the daughter-cells before their liberation from the inclosing 

 mother-cell-wall. 



E. Hamatococcus lacustris, showing nucleus (), single large 

 pyrenoid (f>yr), and contractile vacuole (c.vac), 



F. Diagram illustrating the movement of a flagellum : ab, its base 1 ; 

 c, c', c", different positions assumed by its apex. (E, after Biitschli. ) 



