RESULTS OF COLONY FORMATION 



43 



Sphaerozoum (Fig. 12), which floats about in the surface waters of 

 the open ocean and has in each of its component cells a supporting 

 skeleton of branched siliceous spicules. 



The co-operation of a larger or smaller number of cells to form 

 a colony at once opens up new possibilities with regard to 



FIG. 11. Volvox aureus. (From Weismann's "Evolution Theory," after 

 Klein and Schenck.) 



A, mature colony containing daughter colonies (t) and ova (o) ; B, group of 32 developing 

 spermatozoa seen end on ; C, the same seen sideways ; D, mature spermatozoa, 



differentiation and division of labour. If a sufficiently good 

 understanding, so to speak, can be established between the 

 different members (or zooids) of the colony it will no longer be 

 necessary for each one to do everything for itself. At the expense 

 of becoming mutually dependent upon one another they will be 

 able to specialize in different directions, some identifying them- 

 selves with one necessary duty or function and some with 



