314 GREAT MEN OF SCIENCE 



It is particularly noteworthy that the general law of the 

 conservation of energy has been found to be followed by all 

 living beings, a fact already thoroughly considered by 

 Robert Mayer. He already pointed out that the muscle 

 transforms the chemical energy of the food brought to it by 

 the blood directly into mechanical energy, whereas the steam 

 engine, and all similar motors, make use of the intermediary 

 of heat. The discovery of the second law of thermo- 

 dynamics, by Carnot, Clausius, and Kelvin, has made this 

 a certainty; for in the muscle the differences of temperature 

 are absent, which are essential for the action of heat engines, 

 and which determine their efficiency. The efficiency of the 

 molecular muscle machines is therefore actuallv much 

 greater than that of the best heat engines. 



Summarising what we have said so far, life is, at the last 

 resort, bound up with peculiar molecules, which are con- 

 tained in the cells, in structures visible under the microscope, 

 and beyond this fundamental secret, the phenomena of life 

 do not offer anything fundamentally new in kind. The 

 enormous industry of observers has further brought to light 

 an almost limitless number of single facts, relating to the 

 various species of plants and animals, their constitution, and 

 their life history. Here it is of the highest importance to 

 order the facts in ^n accessible manner. The first great 

 constructor of systems and summariser of knowledge in the 

 domain of living things, and on the basis of his own observa- 

 tion, was Carl Linnaeus; but he only appeared fifty years 

 after Newton's Principia. 



Linnaeus was born in 1707 as the first son of a country 

 clergyman near Verjo in the south of Sweden, and studied 



suited to a comprehension of life, with its coming and going of ever new, 

 and also differently constituted, forms, and with its phenomena, which so 

 obviously transcend everything observed in lifeless matter and in ether. 

 These ideas could be of benefit for the further investigation of life, in the 

 first place chiefly of the sub-microscopic forms which must be assumed, 

 without any injury to the continued pursuit of what is more directly 

 accessible to the senses. 



