MODERN SCIENCE. 125 



functions of organs Boerhaave studied the very materials of 

 those organs, thus extending the area of chemistry, which 

 since Giaber had remained inorganic. He did more ; for after 

 discovering the components of plants, he also found the 

 source out of which plants derived their materials, viz. the 

 chemical substanceswhich made them up out of the soil through 

 the roots, and out of the air and sunshine through the leaves. 

 Likewise, by analysing milk, blood, bile, chyle, lymph, he 

 showed animals to derive their materials from plants, or 

 altered vegetable matter. His determinations were neither 

 perfect nor complete, owing to the ignorance as yet prevailing 

 as regards the constitution of plants, since chemists had not 

 yet discovered the four gases (carbonic acid, hydrogen, nitro- 

 gen, and oxygen) which enter into their composition ; but he 

 nevertheless opened a new branch the chemistry of life and 

 was therefore one of the chief instructors of the age. Among 

 the numerous facts he elucidated, he demonstrated the 

 phenomena of animal structure to be in accordance with the 



LAWS OF MECHANICS. 



1708 77. Haller, a pupil of Boerhaave just as famous as 

 his master, made the Gottingen university a centre of 

 physiological science. Leaving aside the 180 volumes on 

 science he published with the help of his pupils, and the 

 masterly drawings which illustrate most of them, we owe to 

 him the discovery of the POWER OF MUSCLES TO CONTRACT; 

 he found the cause of their contraction to be due, not to the 

 nerves only, but also to independent irritation. He studied 

 the physiology of the human body in a masterly manner. 

 His services to COMPARATIVE ANATOMY were very extensive 

 and important : he was the first to make this branch a 

 separate science. He also collected material for the complete 

 description of the FLORA OF SWITZERLAND. 



1720 93. Bonnet added a great deal to the knowledge 

 of the GROWTH of plants and animals ; made a vast number 

 of observations and experiments, and discovered vegetables 

 to have the power of seeking and finding that which is 

 indispensable to their development moisture, air, and 

 sunlight a department which Darwin will investigate fully, 

 and a fact which is accounted for by law. Bonnet also 



