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solution he proposes is that the system will divide into new spheres when the
membrane grows sufficiently to close in on itself and bud. 20
The metabolic and membrane (including membrane generation) systems
together give rise to what Gánti characterizes as a supersystem which exhibits
biological features:
We have combined two systems of a strictly chemical character into a
'super-system' (or, to put it another way, we have combined two chemical subsys-
tems), and we have obtained a system with a surprising new property of expressly
biological character. What can this system do? It is separable from the external
world and its internal composition differs from that of the environment. It con-
tinuously consumes substances that it needs from the environment which are
transformed in a regulated chemical manner into its own body constituents. This
process leads to the growth of spherule; as a result of this growth, at a critical size
the spherule divides into two equal spherules, both of which continue the process.
(p. 105)
But, according toGánti, this systemis still not livingbecause it lacks an information-
storing or control subsystem. 21 Gánti proposes to provide an information-storing
subsystem by having the metabolic system also add a monomer to a polymer
that is built along an existing polymer template. The length of the polymer is
thereby able to carry information about the number of cycles completed. 22
(See
Fig. 4 for Gánti's portrayal of the complete chemoton.)
Gánti seems to have been led to insist on this third subsystem only because
such an information storage system, in the form of DNA, has been found in
extant organisms: 'This property is not one of the classical life criteria, but on
the basis of knowledge gained from molecular biology, it has been selected as an
absolute life criterion' (p. 106). Gánti in fact says little about what the information
system is to be employed for and one might ask why such an information system
is required in a living system. An appreciation of its significance is provided
by Gánti's own coupling of the notions of information and control. In the
two-component supersystem, the metabolic and membrane systems were strictly
20 Gánti's account of the membrane is overly simplistic. In order to deal with the osmotic crisis that results
from concentration differences inside and outside the enclosure and the tendency of water to spontaneously
enter the enclosure, resulting in its swelling-bursting, the membrane must from the outset be active in pumping
materials in and out (Ruiz-Mirazo & Moreno, 2004, p. 244).
21 James Griesemer and Eörs Szathmáry include marginal notes accompanying Gánti's text, and Griesemer
notes at this point that, had Gánti not been focused on a template-based information system, he could
have included an information encoding structure within the membrane system by allowing, for example, the
incorporation of a variant molecule into the membrane that will be replicated as the membrane is replicated,
resulting in what Jablonka and Lamb (1995) describe as a 'structural inheritance system'.
22 Griesemer provides some suggestions as to how polymer length carries information. For example, if one
molecule is added to the polymer at each turn of the metabolic cycle, it can provide a more reliable indicator
of the growth that has already occurred and when the next division should occur.
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