ZOOLOGY AS A SCIENCE 



n 



heart in the veins (Fig. 1-5). His most im- 

 portant contribution was to prove mathemat- 

 ically that the blood must circulate through 

 the body in this fashion. He went about 

 demonstrating his theory, much the same as 

 it would be done today in a modern re- 

 search laboratory. He computed that at 

 each beat, the human heart delivered about 

 two ounces of blood; beating at 65 times 

 per minute, in an hour it would force about 

 50 pounds of blood through itself. He rea- 

 soned that such a tremendous quantity of 

 blood simply had to stay within the body 

 and circulate from one part to the other. He 

 was able to work out the pulmonary circu- 

 lation cjuite satisfactorily, but he was forced 

 to guess at the existence of body capillaries 

 because, lacking a microscope, he never 

 saw them. Truly Harvey was a great scien- 

 tist, and his courage put physiology on its 

 first step toward the profound science it is 

 today. He brought experimentation based 

 on mathematics into the study of biology 

 for the first time, and has been looked upon 

 as the founder of modern physiology. 



The values of direct observation and ex- 

 perimentation gradually became obvious to 

 the intelligent world in the years following 

 Harvey's initial steps. All through the nine- 

 teenth century brilliant men added their 

 influence to the growing infant science of 

 physiology until it gained full stature at the 

 turn of the twentieth century, and it has 

 been growing steadily up to the present. 

 During the nineteenth century most biolog- 

 ical work was morphological, that is, the 

 study of form and structure of animals; 

 today physiological problems are receiving 

 most of the attention. Biologists are prima- 

 rily concerned with the way animals func- 

 tion. In order to find answers they have 

 been forced to rely on the sister sciences of 

 physics and chemistry, for it has become 

 increasingly obvious that in the last analysis 

 these sciences are most likely to give us the 

 solution to our most profound problems. 



Using these four men, Aristotle, Galen, 

 Vesalius, and Harvey, as examples spaced 



Fig. 1-5. These are two of the original sketches made by 

 Harvey in his little book describing the circulation of 

 the biood. The figures demonstrate the valves in the 

 veins that permit the blood to flovt^ only toward the 

 heart. 



over nearly 2,000 years, it is possible to see 

 how the science of zoology took root and 

 grew to what it is today. Men could have 

 been selected from other sciences to dem- 

 onstrate the same evolution in a way of 

 thinking. In any case, it is obvious that sci- 

 ence was slow in developing during its first 

 2,000 years. It has grown tremendously 

 since then, however, particularly during the 

 past 200 years, and in this century almost 

 explosively. There seems to be no indication 

 of any abatement in its growth at the pres- 

 ent time, and if properly guided science will 

 certainly help to make this world of ours an 

 almost miraculously beautiful one in which 

 to live. 



WHAT SCIENCE HAS DONE 

 AND CAN DO 



Before we discuss the methods used by 

 the scientist, let us consider for a moment 

 what science has done for people of the 

 world, what it is doing today, and what it 

 could or might do in the future. We can use 

 one example, world population in human 

 beings. Approximately 250 years ago there 

 was a world population of some 600 millions; 

 that number has increased fourfold up to 

 the present time and is now increasing at 

 an unprecedented figure. This means that 

 within the relatively short period of 250 



