164 
PHYSIOLOGY: C. M. CHILD 
It may be noted further that the acquisition of this new character by 
an originally non-saccharose-fermenting strain of B.coli has thus far 
developed only once and then on sodium chloride medium. Cultures 
of the parent organism grown in saccharose broth for a series of gen- 
erations as yet show no gas production or acid production. This partic- 
ular change therefore seems to be due to the intra-cellular or molecular 
changes brought about by non-specific influences and not to a direct 
adaptation to particular environmental conditions. 
A DYNAMIC CONCEPTION OF THE ORGANIC INDIVIDUAL 
By C. M. Child 
HULL ZOOLOGICAL LABORATORY, UNIVERSITY OF CHICAGO 
Read before the Academy, December 7, 1914. Received January 15, 1915 
The organic world exists in the form of more or less clearly defined 
individuals, which may be completely isolated from others as self-main- 
taining organisms, or only partly isolated, like the members of a so-called 
colony among the lower animals and the different buds or growing tips 
and the parts associated with each in the multiaxial plants. A tree, 
for example, consists of a great number of plant individuals organically 
connected with each other. 
In all except the very simplest organic individuals an orderly, definite 
sequence of events in space and time occurs which we call development. 
Development includes the series of changes from the reproductive cell 
or cell mass to the mature form of the organism. On the one hand, the 
organs arise in definite space relations to each other and to certain axes 
or planes which we can draw through the developing organism, and on 
the other hand, development consists in an orderly sequence of events 
in time. Certain regions always precede and others follow in regular 
order. The result of this orderly behavior is an organism of more or 
less definite form and structure, often exceedingly complex and with a 
high degree of constancy in successive generations. In the simplest 
individuals these space and time sequences are either less definite or else 
they are subject to frequent change and replacement by others, but 
in most organisms they are relatively permanent. 
Most theories of the organism have failed to account satisfactorily 
for these orderly characteristics. Either they have simply assumed the 
existence of some sort of mechanism adequate to account for the facts, 
or some 'vitalistic,' i.e., non-mechanistic principle, as a controlHng or 
