INTllOD.] PHYSIOLOGICAL INQUIRIES. 31 



cephalic extremity of the animal, and with it are immediately con- 

 nected the organs of the senses, the inlets to perception. We soon 

 find that the hrain exhibits a subdivision into distinct parts ; and 

 of the relative importance of these parts, and their connexion with 

 the organs of sense, and with the intellectual functions, we derive 

 the most important information from the study of comparative 

 anatomy. 



Haller further assigns the examination of the living animal as a 

 valuable aid in physiological research. Doubtless, many obscure 

 points have been elucidated by experiments on living animals, and 

 discoveries have been made which have greatly contributed to the 

 progress of physiology; but the best physiologists are ever reluc- 

 tant to interrogate nature in this way, knowing that replies elicited 

 by torture are rarely to be depended upon. Very useful know- 

 ledge may be derived from observing the play of certain functions 

 in living animals, or in Man himself, contrasting them in various 

 individuals, and noting the effects of age, sex, and temperament, 

 and ascertaining the influence which other conditions, natural or 

 artificial, may exert upon them. 



The investigation of disease, both during life and after death, is 

 of great value to enable us to appreciate the action of an organ in 

 health. If, for example, as Haller remarks, a particular function 

 be ascribed to a certain part, how can there be a more favourable 

 opportunity of testing the accuracy of such a doctrine than by the 

 examination of a body in which that part was affected with a 

 disease, of which the previous history was known ? If the func- 

 tion in question had been vitiated, or destroyed, it may be fairly 

 presumed to have had its seat in the diseased organ. Nothing has 

 contributed more largely to determine the functions of particular 

 nerves, than exact histories of the symptoms during life, in cases 

 in which they had been found, after death, in a diseased condi- 

 tion. 



For exploring the minute structure of various textures, the ana- 

 tomical elements of the body, Haller advises the use of the Micro- 

 scope. The great improvements which modern opticians have 

 accomplished, not only in the dioptric but also in the mechanical 

 adjustments of this instrument, render it an invaluable adjuvant 

 in physiological research. We shall have frequent occasion in the 

 following pages to refer to anatomical analyses, effected by the 

 microscope, of the utmost value to the knowledge of function. 

 It may, however, be remarked, that, as the sources of fallacy 

 aro numerous even with the best instruments, more depends upon 



