324 SCIENTIFIC APPARATUS. 



The progress of anthropology has required the accurate 

 determination of the form and dimensions of the various parts of 

 the human body, and attention may be directed to the complete 

 set of appliances for this purpose (No. 3,999). 



Important improvements have been made in the arrangements 

 for the exhibition of specimens in museums, and especially in 

 mounting skeletons in such a manner that the separate bones can 

 be detached and examined upon all sides (3,812), and many 

 admirable examples of anatomical and zoological models and 

 diagrams are exhibited. 



As it is the object of the physiologist to ascertain the pro- 

 perties and the modes of action of living matter and to explain 

 them, so far as they are explicable, by deduction from the laws of 

 physics and chemistry, he is necessarily dependent upon observa- 

 tions of, and experiments upon, living matter for the data upon 

 which his reasonings are founded. 



Among phenomena of so complex a character, simple observa- 

 tion goes but a very little way, and our knowledge of all the 

 most important truths of physiology has been obtained, as the 

 student of the History of Science is well aware, by experimenta- 

 tion upon living plants and living animals. 



The older physiologists obtained only qualitative results from 

 their experiments. They determined the nature, but not the 

 amount, of the forces exerted by the tissues; they ascertained 

 the quality and general character of the secretions and excretions, 

 but neither the exact composition nor the precise quantity of 

 the matter secreted or excreted. 



The experiments of Hales and of Priestley led the way to 

 quantitative determinations of the effects of physiological processes, 

 but the present generation has seen the greatest advance that 

 has yet been made in physiology the application of instruments 

 of precision to this end. 



From this point of view a singular interest attaches to the 



