Science in Conservation During War Times 59 
to popular notions, some of which may not be wholly sound. 
While continuing these practices, it is launching fact-finding in- 
vestigations using methods which are recognized as conforming 
to the requirements of scientific procedures. The application of 
such scientific methods is Being introduced as rapidly as the 
^'traffic will bear/' but it is significant that the practices and pro- 
cedures adopted arc being determined by and based on reliable 
scientific facts. It is to this end that a brief insight into the 
analysis of an aquatic environment is now^ presented. 
An aquatic environment is the end result of all conditions 
and factors existing within the entire watershed which furnishes 
water to supply a medium in which life exists. Sometimes the 
watershed is so far removed from the water medium that its 
source cannot be determined, as in the case of streams fed by 
springs whose sources ma}^ be in far away solution basins. Never- 
theless, the habitat is directly dependent on and affected by it, 
and the chemical composition of aquatic solutions can be only of 
those chemicals with which the water has contact, 
I 
No life can exist for any length of time in pure water. 
Chemical substances must be supplied to the water if it is to 
support life. These chemicals, either organic or inorganic, are 
the foundation for the ladder of aquatic life extending from 
microscopic plankton through the invertebrates up to the large 
vertebrate animals. Since the bodies of plants and animals are 
composed of complex chemical compounds, there must be a chem- 
ical reservoir from which the building-materials of these com- 
pounds can be obtained. The watershed, including soils, plant 
and animal debris, and atmospheric suspensions, is the reservoir 
from which life-building elements are drawn. The water, falling 
as rain and later running off, serves as the transporting solvent, 
moving the dissolved or suspended chemical substances into the 
stream, which in this case is taken as the biotic medium. 
Micrpscopic or semi-microscopic organisms living within this 
medium take these chemicals directly into their cells by ingestion 
of colloids or diffusion of solutes for use in their chemical or 
physical make-up. These small living aquatic forms, generally 
known as plankton, furnish the chemical foundations on which 
the higher aquatic life is built. Larger organisms, usually visible, 
depend on the plankton for substance and in turn are consumed 
by higher forms of life, such as small fish, insect larvae, worms, 
shrimps, amphipods and other similar animals. This might be 
compared to the middle rungs in the ladder of aquatic life, while 
the upper rungs are represented by the larger aquatic vertebrates 
