DIMORPHISM 35 



We see the very first step towards a division of labour in 

 the minute organism now under consideration. If we could 

 cut off a pseudopod of Amoeba the creature would be little 

 or none the worse, since every part would be capable of 

 sending off similar processes, and so movement would be in 

 no way hindered. But if we could amputate the flagella of 

 Hsematococcus its movements would be absolutely stopped. 



Hsematococcus multiplies only in the resting condition 

 (p. 28, and Fig 3, B) ; like Amoeba its protoplasm undergoes 

 binary fission, but with the peculiarity that the process is 

 immediately repeated, so that four daughter- cells are pro- 

 duced within the single mother-cell-wall (Fig. 3 c). By the 

 rupture of the latter the daughter-cells are set free as the 

 ordinary motile form ; sometimes they acquire their flagella 

 and detached cell-wall before making their escape (D). 



Under certain circumstances the resting form divides into 

 eight 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. Haematococcus is therefore dimorphic, 

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

 the larger or ordinary form with detached cell- wall is called a 

 megazooid, the smaller form without a cell-wall a microzooid. 



D 2 



