XIT 
ON THE LIMITS OF DIVISIBILITY OF LIVING MATTER! 
1. THE progress which has been made in physics and 
chemistry as the result of our modern conceptions of mole- 
cules and atoms suggests the possibility that a more definite 
insight into the limits of divisibility of living matter might 
also be of importance for the development of physiology. 
As a criterion for ‘living matter” we might use the irrita- 
bility or spontaneity. But as the “spontaneity” of living 
matter is in its simplest form (in Amcebe) apparently not 
different from the physical phenomenon of spreading, for 
this criterion the limits of divisibility of living matter coin- 
cide with the limits of this purely physical phenomenon. 
But spontaneity is neither the deepest nor the most essential 
life-phenomenon; development— or, in other words, growth, 
organization, and reproduction—occupies this place. If we 
ask how the ultimate elements of living matter are con- 
stituted which still possess the specific morphogenetic prop- 
erties, the excellent papers of Nussbaum give us a qualitative 
answer. This investigator found in experiments on the 
divisibility of an Infusorian, Gastrostyla, that only such 
pieces are able to regenerate into a complete animal as con- 
tain nuclear material. 
For the preservation of an Infusorian it is immaterial whether 
it is divided longitudinally, transversely, or obliquely; if only a 
portion of the nucleus is retained, the fragment regenerates into its 
original form in less than twenty-four hours, depending upon the 
temperature. As soon as twenty minutes after division the cut 
edges form new cilia, and upon the following day each of the 
pieces containing nuclear material possesses from four tosix nuclei 
and nucleoli, and all the ciliary appendages characteristic of the 
species.’ 
1 Pfligers Archiv, Vol. LIX (1894), p. 379, 
2NussBAUM, Archiv fiir mikroskopische Anatomie, Vol. XXVI, p. 514. 
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