96 ANIMAL INDIVIDUALITY [OH. 



independently, can unite into new societies unlike 

 anything known to exist in free nature, and can 

 there subsist for no inconsiderable time. 



So much for the independence of the cells : 

 now for their subordination. If, in the experiment 

 narrated above, all the kinds of cells are allowed to 

 remain mixed after their mutual attachments have 

 been broken, we get a result very different from 

 that obtained with the pure collar-cells. First of 

 all, the cells, many of which are still actively amoe- 

 boid, and can be seen crawling over the bottom, 

 unite with each other into small lumps and balls. 

 These balls are unlike any organisms known to exist : 

 for, although all their constituent parts are alive, 

 they are without any arrangement and cannot execute 

 any concerted function. Now comes the strange part : 

 this higgledy-piggledy of cells joined up at random is 

 able to reorganize itself, to produce order out of chaos. 

 First of all the collar-cells sort themselves out and 

 form a central solid mass, the dermal cells migrate to 

 the exterior and join up into a single dermal layer. 

 By so doing (though they still resemble no known 

 organism), they have laid down the ground-plan of 

 the sponge, for it is of the essence of sponges to 

 consist of these two layers in this position. The 

 subsequent changes are changes of detail ; cells of the 

 outer layer detach themselves and form the spicules 

 between the two layers. Then the inner mass hollows 



