STATE OF SCIENCE—COMPTON 401 
into the substance of life. But who can say whether the answer to 
the secret of photosynthesis may not have more far-reaching effects 
on our lives and on those of generations to come? 
Kenneth Mees, whose book, The Path of Science; presents a suc- 
cinct review of the growth of scientific ideas, places the beginning of 
modern biology in 1838 with the publication by two Germans, 
Schleiden and Schwann, of the cell theory. 
Biological sciences received enormous impetus from the publica- 
tion in 1859 of Darwin’s Origin of Species, but Darwin died without 
ever learning of the important work of Gregor Mendel whose great 
study of heredity shed such interesting light on Darwin’s theories. 
The science of genetics which rests upon the foundation so brilliantly 
laid by Mendel owes much to Belgian zoologist Beneden who dis- 
covered the double sets of chromosomes in each nucleus except the 
reproductive cells. 
It was also in this latter half of the nineteenth century that the 
great German pioneer bacteriologist, Robert Koch, discovered the 
bacilli of anthrax and tuberculosis, that the great French chemist, 
Louis Pasteur, did his pioneering work on germs and ferments, and 
the British Lord Lister developed antiseptic surgery. 
Astronomy at the end of the nineteenth century was largely obser- 
vational, with the discovery and cataloging of stars and nebulae, 
examination of the appearance of sun and planets, and precise calcu- 
lations of orbits. Stellar spectra and brightness were measured with 
routine persistence but without interpretive theories to guide and give 
significance to the observations. 
In the foregoing sketch of science up to the beginning of our twen- 
tieth century I have made no attempt at complete coverage; I have 
even omitted entire fields of science, like geology and psychology. 
I have not discussed practical applications, like engineering and 
medicine. I have only used these few examples to serve as spring- 
boards for the jump into the twentieth century, in which scientific 
progress has forged ahead with ever-increasing acceleration and in 
which the fields of science, hitherto almost separate in their develop- 
ment, have merged more and more toward a single all-inclusive and 
all-interrelated science of the forces and materials of nature. 
The physicists and the chemists both started their twentieth- 
century research with the atom. The physicists have looked into the 
atom to discover how it was constructed and how its parts behaved. 
The chemists piled atoms together to form molecules of all degrees 
of complexity. The work of each reacted on the other, and physicists 
had to learn more chemistry and chemists more physics. And the 
discoveries of each provided new tools for both. 
3 John Wiley & Sons, Inc., New York, 1947. 
