130 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



plete ascidian (Fig. 13). Such a fact certainly seems to 

 be very important, not to say very surprising ; but still 

 another phenomena may be demonstrated on the animal 

 which seems to be even more important. You first isolate 

 the branchial apparatus from the other part of the body, 

 and then you cut it in two, in whatever direction you 

 please. Provided they survive and do not die, as indeed 

 many of them do, the pieces obtained by this operation 

 will each lose their organisation, as did the whole branchial 

 apparatus, and then will each acquire another one, and 

 this new organisation is also that of a complete little 

 Clavellina. So we see that not only is the branchial 

 apparatus of our animal capable of being transformed into 

 a whole animal by the co-operative work of all its parts, 

 but even each part of it may be transformed into a small 

 whole, and it is quite at our disposal how large this part 

 shall be, and what sort of a fragment of the original 

 branchial apparatus it shall represent. 



We could hardly imagine a better instance of an 

 harmonious-equipotential system. 



I cannot give you a description of all the other types 

 of our systems subservient to restitution, and I can only 

 mention here that the common hydra and the flatworm 

 Planaria are very fine examples of them. But to one 

 special case of harmonious equipotentiality you must allow 

 me to direct your further attention. 



It has been known for many years that the Protozoa 

 are also capable of a restoration of their form and organisa- 

 tion after disturbances, if at least they contain a certain 

 amount of their nuclear substance. This process of restora- 

 tion used to be regarded as belonging to the common type 



