292 The. American Geologist. November, i£98 
that he characterized the whole life of the individual as a 
process of senescence or growing old. 
Naturalists have as a rule understood the differences be- 
tween the organic molecular increase that takes place within 
cells, which is t he simplest form of growth, and thai which 
follows this and builds up the tissues of the body by the di- 
vision of cells. Both of these processes, although distinct 
from each other, result in additions to the hulk of the whole 
body of the organism and come properly under the head of 
growth. But while both are thus constructive so far as the 
body is concerned, only one can be considered constructive or 
anabolic, while the other is essentially destructive or catabolic 
so far as the cell itself is concerned. 
The function of nutrition and the nature of the organic 
struct ure are the two essential factors of growth, and this term. 
i. '. growth, also obviously applies to the morphology of met- 
abolism, consisting of intra-cel hilar increase, or anabolism, 
and cellular development, or cataboHsin, and the phenomena 
resulting from the alternating action of these in ontogeny. 
This at once shows that growth is not simply progressive ad- 
dition to the bulk of the body, since the multiplication of 
cells by fission is in itself catabolic or developmental so far as 
the cells are concerned. Further than this the ultimate re- 
sults of catabolism areof the nature of reductionsas is shown 
by Minot's work, by Maupas's observation on the old age of 
the agamic cycle in Infusoria, and the results of late re- 
searches on amitosis in cellular fission. These and the ac- 
tual reduction of the body taking place in extreme senility 
-how. that the term growth covers decrease in bulk due to de- 
velopment and use, as well as increase. 
When one passes beyond this and attempts to deal with the 
characteristics of ontogeny or phylogeny heat once finds him- 
self in the presence of otherforces, such as heredity and other 
processes, namely, the acquisition of new characters and the 
renewal of the powers of growth in nuclear substances by 
means of conjugation. 
The manifestation of growth energy in brief arises from two 
factors, or at any rate, is always found associated with two. a 
living organism and assimilation of nutritive matter, and is 
an obvious result of their union. 
