526 
BIOLOGY AND HUMAN PROGRESS 
teacher will show you how to do. Here are the names of 
these bureaus : The Biological Survey, where they have been 
giving special attention to seals, reindeer, and ground 
squirrels; Bureau of Fisheries, which includes not only fish 
but also clams and oysters as well as lobsters, shrimps, and 
crabs; Bureau of Plant Industry, dealing with a wide range of 
problems connected with fruits, vegetables, cereals, and 
general farm crops; and the Bureau of Chemistry, which 
takes up such questions as sugar manufacture, various sirups, 
and adulterations. 
Many of the results of the discoveries of the experts 
working in the United States Department of Agriculture 
are published as Farmers’ Bulletins and can be secured by 
any one. Write to Division of Publications, Washington, 
D. C., for the list of available bulletins, which will be sent 
free so long as the supply lasts. 
404. New Ideas. — New ideas keep one informed about the 
way other people do and make one broadminded and pro¬ 
gressive. A different way of weaving cloth, a new process 
in the utilization of the stored energy in coal, or a better 
recipe for making bread indicate how a variety of ideas may 
help man to control his environment. Among the most 
fruitful sources of new ideas are the numerous scientific dis¬ 
coveries that are constantly being made. Such discoveries 
are of no value to the masses of the people unless they are 
turned to practical use. 
New ideas are rejected by many people because they do 
not understand the facts that have been discovered. In 
order that we may better understand this important phase 
of biology, we will now examine two interesting subjects, 
variation and heredity, and point out their relation to human 
progress. 
405. Variation. — One of the surest ways to understand 
the scientific meaning of the term variation is to collect 
leaves from any tree. Maple or oak leaves are especially 
