146 ANIMAL INDIVIDUALITY [OH. 



expended in the construction, some of the existing 

 materials must be sacrificed as energy-producers, so 

 that by the time the bit of worm-protoplasm has turned 

 itself into a worm, it has actually decreased in bulk 

 (Fig. 15). The half- worm has never ceased to exist as 

 a half, but has somehow managed to become an ever 

 smaller half while remodelling itself continually and 

 at the same time handing over material for the 

 building of what is missing. Finally the other half 

 is completed a whole worm has been made ; up till 

 now the old half had been decreasing rapidly in size, 

 the new increasing almost as fast. From the time 

 that a whole is formed, both halves behave alike, 

 decreasing slowly together as a result of starvation. 



This and many other similar facts tend to show 

 that the relation of form, and so (since specific form 

 or structure is only the visible machinery of a specific 

 working) of individuality in living things to its 

 physical basis of matter, is primitively a simple one, 

 though one that is at variance with all our precon- 

 ceived ideas. It seems to be this : any separate mass 

 of one kind of protoplasm will be able to, or rather 

 must, make itself into an individual with the form 

 characteristic of the species. The only provisions are 

 that it is neither too large nor too small within certain 

 defined limits and, of course, that the external con- 

 ditions are favourable. 



Facts suggesting this we have seen in Clavellina, 



