THE SCOPE OF ZOOLOGY 



Kidder found that this one-celled protozoan required a substance 

 known as guanine in its food in order to grow. He then tried substi- 

 tuting other substances chemically similar to guanine to see if the or- 

 ganism could grow on these. He found one substance, guanazolo, 

 which Tctrahymcna would absorb in preference to guanine, but it could 

 not use this in its life processes. In other words, we might say that 

 it had been tricked into taking a substitute food which it could not 

 utilize properly and thus its growth was stopped completely. 



Now what possible practical significance could such a discovery 

 have? In higher animals there are sometimes certain cells of the body 

 which grow wildly, out of control of the rest of the body. We know of 

 such growths as cancer. Investigation showed that guanine was neces- 

 sary for the growth of cancer tissue, but was not necessary for the 

 growth of normal body cells. Experiments were then devised with 

 mice that had cancers. Injection of guanazolo into these mice caused 

 a complete inhibition of cancer growth, but did not harm the normal 

 tissues of the bodies of these mice. Perhaps further investigation will 

 show that this can also be used to inhibit cancer growth in human 

 being's. If so, this will be a milestone in our fight against cancer — 

 and all because a man wanted to find out about the nutrition of a one- 

 celled animal. 



Millions of dollars have been spent on directed research designed to 

 find methods of relieving cancer, yet this one discovery which was 

 not directed against cancer at all may have greater value than any of 

 the other findings. Over and over again results similar to these have 

 emphasized the impracticality of a narrowly planned program of sci- 

 entific research. Science must always be free to investigate, without 

 restrictions, any subjects which fall within the scope of its methods and 

 to derive conclusions based on impartial findings or it will cease to be 

 a science. 



The Divisions of Science 



When we use the word "science" without any descriptive adjective, 

 we usually refer to the natural sciences which deal with natural phe- 

 nomena in contrast to social sciences, such as sociology, which deal 

 with human relations, or the abstract sciences, such as mathematics, 

 which deal with abstract subjects. The natural sciences are further 

 broken down into physical sciences and biological sciences. The physi- 

 cal sciences relate primarily with nonliving matter and include such 

 subjects as physics, chemistry, geology, and astronomy. The biological 

 sciences deal with living matter and include botany and zoology as major 



