1892.] Heredity of Acquired Characters. 891 
steps of its elaboration, and the katastates resulting from its 
destructive metabolism in the same individual, must vary 
with the ever changing conditions of the environment, and 
the functional activity of every part of the organism. Indi- 
vidual variations from the prevailing type of the group, or 
family, are then readily accounted for by a disturbance in the 
symmetrical balance of the metabolism of the different organs 
of the body, by prevailing habits, or changes in the environ- 
ment and conditions of food supply. 
In the phases of life from the embryo to the final decline of 
the bodily powers, there are changes in the relative predomi- 
nance of anabolic and katabolic activities that we should not 
fail to notice. 
In Dr. Minot’s interesting address at Indianapolis “ On Cer- 
tain Phenomena of Growing Old,” the sequence of mutations 
in metabolic activities in the life of the individal were clearly 
shown. The greater activity of the nutritive functions in 
youth, and their gradual decline to maturity and old age were 
strikingly illustrated by an instructive series of statistical dia- 
grams. It was also shown “that with the increasing develop- 
ment of the organism and its advance in age, we find an 
increase in the amount of protoplasm.” This apparently con- 
flicts with the conception of protoplasm as the physical basis 
of lifé, and the most plausible inference from these facts, as 
suggested by Dr. Minot, was that “the development of proto- 
plasm is the cause of the loss of power of growth,” and that 
“protoplasm was the physical basis of advancing decrepi- 
tude.” 
A less obvious, but more satisfactory, explanation is fur- 
nished in the outline of the processes of nutrition already pre- 
sented. It is evident that protoplasm is but a way station, as 
it were, in the development of tissues, and its destructive met- 
abolism is an indispensable condition of growth, and increase 
of organic substance. The greatest activity of the katabolic 
phases of metabolism take place in the embryo and youth, 
and they then keep pace with the anabolic, or constructive 
processes of the organism, so that the protoplasm elaborated is 
used in tissue building as fast as it is formed. When maturity 
