98 HISTORY AND SIGNIFICANCE OF SCIENCE 



The advance of biological science during the century under 

 discussion was mainly important as a preparation. The 

 Cell-Theory was not formulated until the second quarter of 

 the nineteenth century. Organic Evolution was not gener- 

 ally accepted until the publication of Darwin's " Origin of 

 Species" (1859). The development of biological science 

 during the closing centuries of the Renaissance has already 

 been summarized. During the eighteenth century, the facts 

 regarding the number and kinds of animals and plants were 

 organized by Linnaeus (1707-1778). His was the first system 

 of classification which pretended to an arrangement of all the 

 known forms of life. If Linnaeus did not originate the 

 binomial nomenclature, 5 by which each kind of animal is 

 given a double name, he may be said to have established its 

 use. His general scheme, of species, genera, and families 

 exists at the present day, despite the progressive changes in 

 the larger groupings and the wholly new concept of classifi- 

 cation which was necessitated by the doctrine of evolution. 

 Linnaeus introduced order into the study of animal life, and 



it was a good theory for the time being and did not hamper chemical progress 

 in many lines. It was finally overthrown when Lavoisier (1743-1794) showed, 

 by means of the balance, that combustion was a process and not a substance, 

 since it possessed no weight. The way was then open for the establishment of 

 the atomic theory through the work of Dalton (1808). At the present time 

 physicists speak of the structure of the atom, of the continuous ether, and of 

 all matter as energy, and even challenge the philosophers with interesting 

 theories of ultimate reality. But despite modifications, the atomic theory 

 with its concept of relatively indivisible atoms, which combine into molecules, 

 is the working assumption of physico-chemical science. The atoms and the 

 void, now called the ether, have never been seen. Belief in their existence, 

 despite the fact that it explains visible phenomena, is a theoretical generaliza- 

 tion which is useful because it gives a summary basis for the explanation of 

 tangible facts. 



6 Here, as elsewhere, use of a second or even a third name had been 

 made as a matter of course. It now became universal in biological science. 

 Its value lies in the fact that the naming can be more definite the greater the 

 number of names applied. But more than two is cumbersome. Thus we 

 speak of the Smiths, and to be specific, of John Smith; going further, of John 

 Henry Smith: just as we designate the cats, Felis, and the domestic cat, Felis 

 domestica. 



