34 H/EMATOCOCCUS LESS. 



the flagellum bends to the left side ac becomes shortened, 

 as it bends to the right the side be. 



This may be otherwise expressed by saying that in bend- 

 ing to the left the side ac contracts (see p. 10), in bending 

 to the right the side be, or that the movement is performed 

 by the alternate contraction of opposite sides of the 

 flagellum. 



Thus the ciliary movement of Haematococcus, like the 

 amoeboid movement of Amoeba, is a phenomenon of con- 

 tractility. Imagine an Amoeba to draw in all its pseudo- 

 pods but two, and to protrude these two until they became 

 mere threads; imagine further these threads to contract 

 regularly and rapidly instead of irregularly and slowly ; the 

 result would be the substitution of pseudopods by flagella, 

 i.e., of temporary slow-moving processes of protoplasm by 

 permanent rapidly-moving ones. 



To put the matter in another way : in Amoeba the 

 function 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. We have therefore in Haematococcus a dif- 

 ferentiation of structure accompanied by a differentiation of 

 function or division of physiological labour. 



The expression " division of physiological labour " was 

 invented by the .great French physiologist, Henri Milne- 

 Edwards, to express the fact that a sort of rough correspond- 

 ence exists between lowly and highly organized animals 

 and plants on the one hand, and lowly and highly organized 

 human societies on the other. In primitive communities 

 there is little or no division of labour : every man is his 

 own butcher, baker, soldier, doctor, &c., there is no distinc- 

 tion between "classes" and "masses," and each individual 

 is to a great extent independent of all the rest. Whereas in 



