250 H.T^.MATOCOCCUS cHAr. 



Each flagcllum (Fig. 68, a,/) is a thread of protoplasm 

 of uniform diameter except at its distal or free end, where 

 it tapers to a point. The lashing movements are brought 

 about by the flagellum bending successively in different 

 directions (f). Thus the ciliary movement of HEematococ- 

 cus, like the amoeboid movement of Amceba, is a phenome- 

 non of contractility. Imagine an Amoeba to draw in all its 

 pseudopods but two, and to protrude these two until they 

 became mere threads ; imagine further these threads to 

 contract rapidly and more or less regularly instead of slowly 

 and irregularly ; the result would be the substitution of 

 pseudopods by flagella, i.e., of temporary slow-moving pro- 

 cesses of protoplasm by permanent rapidly-moving ones. 



To put the matter in another way ; in Amceba the func- 

 tion of contractility is performed by the whole organism ; 

 in Haematococcus it is discharged by a small part only, viz., 

 the flagella, the rest of the protoplasm being incapable of 

 movement. 



Hpematococcus multipHes after becoming quiescent or 

 in the encysted condition (Fig. 68, c, d) ; as in Amoeba its 

 protoplasm undergoes simple or binary fission, but with the 

 [leculiarity that the process is immediately repeated, so that 

 four daughter-cells are produced within the single mother- 

 cell-wall. By the rupture of the latter the daughter-cells 

 are set free as the ordinary motile form, acquiring their 

 flagella and detached cell - wall before making their 

 escape (ri). 



Under certain circumstances the resting form divides into 

 eight or more instead of four daughter-cells, and these when 

 liberated are found to be smaller than the ordinary motile 

 form, and to have no cell-wall. Hrematococcus therefore 

 occurs, in the motile condition, under two distinct forms, i.e., 

 is dimorphic : the larger or ordinary form with detached 



