ir DIMORPHISM 35 



complex civilized communities society is differentiated into 

 politicians, soldiers, professional men, mechanics, labourers, 

 and so on, each class being to a great extent dependent on 

 every other. This comparison of an advanced society with 

 a high organism is at least as old as ^Esop, who gives 

 expression to it in the well-known fable of "the Belly and 

 Members." 



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 

 Hcematococcus its movements would be absolutely stopped. 



Haematococcus multiplies only in the resting condition 

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

 simple or binary fission, but with the peculiarity that the 

 process is immediately repeated, so that four daughter-cells 

 are produced within the single mother-cell-wall (Fig. 3 c). 

 By the rupture of the latter the daughter-cells are set 

 free in 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 or even more daughter-cells, and these when liberated 

 are found to be smaller than the ordinary motile form, and 

 to have no cell-wall. Hcematococcus is therefore dimorphic, 

 i.e., 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. 



