38 ANIMAL INDIVIDUALITY [CH. 



free-living animals, the Protozoa, including all the 

 simplest forms known, which correspond in all 

 essentials, save their separate and independent 

 existence, with the units building up the body of 

 man : both, in fact, are cells, but while the one 

 seems to have an obvious individuality, what are 

 we to say of the other ? 



So far we have treated the problem statically, as 

 it were : when we come to view it dynamically, 

 tracing the movement of life along its course, the 

 difficulties do but increase. Take, to begin with, a 

 simple colony of Hydroid polyps (Fig. 2), and ask how 

 does this multiplicity of connected animals arise ? 

 Observation shows the whole stock to be formed, by 

 a process of budding, from one original individual. 

 A little lump or knob is seen at one place, which, 

 growing rapidly, bit by bit assumes the appearance 

 of the individual whence it has sprung ; it takes its 

 origin in a small group of cells (not in a single one) 

 and its growth depends on continued growth of the 

 substance of these cells, accompanied by their re- 

 peated division. By this means, the first individual 

 produces a second out of itself. Its own individuality 

 is not lost in the process ; it is, however, impaired, 

 for though the creature's organization is practically 

 the same as it was before, yet it is no longer separate 

 in space, and that part of it below the bud's point 

 of origin is now the common property of the two 



