No. I.] REGENERATIVE ENERGY. 49 
neous or artificial division, possess the same formative power as 
did the undivided organism. But it must be remembered that 
most organisms do not admit of such division, and that in those 
that do admit of it, everything depends on how the division is 
made. The extra-capsular portion of a Radiolarian does not 
reproduce the central capsule, nor does the non-nucleated frag- 
ment of an infusorian regain its lost parts. Even here, then, it 
is not permissible to disregard the physiological correlation of 
parts, since both nuclear and cytoplasmic elements are indis- 
pensable to the preservation of the formative power. We still 
have to regard such organisms as physiological wholes, although 
the physiological connexus may be representable in aliquot 
parts. 
The principle holds true of every organism, irrespective of 
whether the mass is divided into cells or not. The fact that 
physiological unity is not broken by cell-boundaries is confirmed 
in so many ways that it must be accepted as one of the funda- 
mental truths of biology. 
