alte

4. Repetition of evolutionary stages of the race.

ae Primitive nervous system

be. Primitive muscular system

ec. Primitive circulatory system

d. Later development of special organs.

De The mature foetus.
D. PRENATAL PERIOD

The prenatal period extends from the moment of conception to the moment of
birth. In considering the development of the new individual, remember that
from the instant of conception the fertilized cell fuses with no other cell;
it takes into itself no further living substance. It begins manufacturing
its own protoplasm from the food substances it receives from the mother.
The book of heredity for the individual is closed at conception. But the
book of environment is just opening. | sara ae aa

 

E. NATAL PERIOD

During the 280 days of parasitic life the human foetus has carried forward
its processes of nutrition, respiration (internal), excretion, and growth
at the expense of the mother. hen comes the phenomenon of birth or separ-
ation of the foetus and its appendages from the body of the mother. It is
a hazardous and momentous change for this infant, when it suddenly is cast
into the outer world to take up its independent existence.

REFERENCES: *Kirkpatrick and Huettncr--Fundamentals of Health, Pp. 34-55, 411-450.
Martin--Human Body, Pp. 592-613. ,
Conklin--Heredity and Environment, Chap. 1
Guyer--Being Well Born, Chap. 4
Dorsey--Why We Behave Like Human Beings, Chap. 1
MeMurrich, J.P.e--Development of the Human Body

*Required reading.

F. HEREDITY AND ENVIRONMENT - GROWIH AND DEVELOTMENT (the first determing force
of Constructive Hygiene)

From the moment of conception this new individual has been subject to two
forces: Heredity or Nature, and Environment or Nurture. The great problem
of development is the unraveling of the effects of these two and the assign-
ment of its true value to cach. Through ages of speculation and scientific
research these relationships have fascinated man and have given rise to an
immense volume of investigation.

1. Environmentalist View

 

Early thinkers believed that species might be transmuted by envi-
ronmental changes and that life itself could arise from lifeless
matter. Philosophers of the 17th and 18th centuries believed that
man was the product wholly of environment.

2e Hereditarian View
Modern biology has been responsible for the establishment of the

vital importance of heredity both to the race and to the indivi-
dual, It has failed to produce life artificially or to create