416 Account of M. Bichat'sTheory of Ijfe. f June I, 



wliich he has, by means of it, thrown 



around many of those pliaMiomena. 



In the first ])lacc, as he teaches ns, 

 the two lives diii'er, in some important 

 respects, as to the or<<ans by which 

 their functions are performed. Those 

 of the animal life present a symmetry 

 of external form, stronslj' contrasted 

 ■with the irreo;ulariiy, wliich is a promi- 

 nent characteristic of those of organic 

 life. In the animal life, every function 

 is either performed by a pair of organs, 

 perfectly similar in slrucfure and si;^c, 

 situated one upon each side of the 

 median dividing line of the body, or 

 else by a single organ divided into two 

 similar and perfectly symmetrical 

 halves by that line. Thus the organs 

 of sight and hearing, and of loconio-. 

 tion, arc double and similar ; the 

 nerves of the brain go off in coitcs- 

 ponding pairs; the organs of smell and 

 taste, and the brain, arc situated with 

 a perfect regard to this law. The 

 organs of the m-t/anic life, on the con- 

 trary, present a picture totally dif- 

 ferent; they are irregularly formed, 

 and irregularly arranged ; the stomach 

 is disposed without any regard to the 

 median line, and one half of it bears no 

 resemblance to the other; the same is 

 true of the liver, the spleen, and all the 

 organic viscera. The heart, it is true, 

 is a double organ ; but its parts are of 

 unequal size and strengtii ; the rest of 

 the circulating system ]Mcsents a thou- 

 sand irregularities ; and the lungs are 

 dissimilar in the two sides of the 

 thorax, in the division of their lobes, 

 and the quantity of matter tljey 

 contain. 



This symmetry of the form is accom- 

 panied by a corresponding harmony in 

 the functions of the organs of tlie ani- 

 mal life. The exactness and perfec- 

 tion of vision depend upon the simila- 

 rity of the impressions transmitted by 

 the two eyes to tlie brain ; if these im- 

 pressions are dissimilar, vision will be 

 imperfect in j)roportion ; hence we 

 shut one eye when the power of the 

 other is increased by the interposition 

 of a lens, and hence we squint when 

 one eye is made weaker than the 

 other. The same is true of all the 

 senses, of the nniscles of locomotion 

 and voice, and of the brain itself; if 

 there is between the corresponding 

 organs on the two sides, or the corres- 

 ponding halves of the organs, any ine- 

 quality or dissimilarity, that is, if there 

 be any defect of symmetry, the conse- 



qucnoc is an imperfection in their 

 function. Upon this principle Bichat 

 explnins the diflerence between dififer- 

 ent individuals in their natural capa- 

 city for distinguishing accurately the 

 harmony of sounds. A good ear for 

 music, as we express ourselves in com- 

 mon language, is only the result of the 

 possession of two symmetrical organs 

 of hearing, which transmit to the 

 brain similar impressions ; a bad ear, 

 on the contrary, is produced by any 

 inequality in the organs, which trans- 

 mit two unequal impressions. Thus, 

 when one, either of our ears or eyes, is 

 deprived of its usual degree of sensi- 

 bility, we can hear or see much belter 

 by making use of that alone which is 

 uninjured, than by having recourse to 

 both. The same remark is extended 

 to the functions of smelling, tasting, 

 and touching, and to the functions of 

 the brain and muscles. But nothing 

 like this is true of the organic life, to 

 the regularity of wiiose ojjcrations, 

 harmony and correspondence of action 

 is not a necessary condition. 



Tlic functions of the organic life are 

 constantly going on ; they admit of no 

 interruption, no repose ; wl-.atevrr 

 cause suspends, but for a moment, the 

 respiration or the circulation, destroys 

 life. They form a necessary and con- 

 nected scries, which must be always 

 moving on in continued progression, 

 from the beginning to the end of exist- 

 ence. But in those of the animal life 

 the case is widely different. They 

 have intervals of entire repose. The 

 organs of this life are incapable of 

 constant activity, they become fa- 

 tigued by exercise, and require rest. 

 This rest, with regard to any particu- 

 lar organ, is the sleep of that organ ; 

 and in proportion to the extent of the 

 previous exercise, and the number of 

 organs fatigued, the state of repose 

 will be partial or general. Upon this 

 principle Bichat founds his theory of 

 sleep. General sleep is the combina- 

 tion of the sleep of particular organs. 

 Sleep then is not any definite state, 

 but is a more or less complete rest of 

 the whole system in proportion to the 

 number of organs which require re- 

 pose. The most perfect sleep is that 

 where all the functions of animal life, 

 the sensations, the perception, the 

 imagination, the memory, the judg- 

 ment, locomotion, and voice, are sus- 

 pended; and the various forms of im- 

 perfect sleep exhibited in dreaming, 



som- 



