2 GENERAL PHYSIOLOGY. 



chemical phenomena resembling in every respect those pro- 

 duced by inanimate nature : thus, the eye is a physical and 

 dioptric apparatus ; the transformation of starch into sugar, 

 in the mouth, is a purely chemical fact. But we meet, 

 besides these, phenomena which can be explained neither 

 by chemistry nor by physics: these phenomena deserve a 

 separate study, and should constitute a special science in 

 a department whose bounds are unlimited. Such phenom- 

 ena are, properly speaking, vital: but at this present time 

 we can only give a purely negative definition of life ; 

 viz., life is all that cannot be explained by chemistry or by 

 physics. 



But, whilst all the chemical and physical phenomena are 

 localized in those portions of the apparatus that are simply 

 mechanical or non-globular (fibres, vessels, etc.) ; whilst 

 these apparatus present to us always the same essential 

 aspect, and whilst, for example, a fibre taken all by itself 

 can often offer no characteristic features by which we can 

 designate it as young or old, yet the phenomena which 

 are neither chemical nor physical, in other words, vital phe- 

 nomena, are localized in the globules or cells, so for as we 

 can now by the process of elimination suppose ; this is also 

 confirmed by observation ; these elements are presented to 

 our view as continually undergoing changes ; possessing an 

 ephemeral existence they undergo metamorphoses of form 

 and of composition, from the moment which we can call 

 their time of birth to that which constitutes the time of 

 death ; in short they are endowed with age. This is pre- 

 cisely the essence of those phenomena which can be ex- 

 plained neither by chemistry nor by physics, so that we can 

 say life is the correlation of successive phenomena presented 

 by the globular element, and can define in a positive manner 

 the word physiology, as the study of the globular element in 

 its metamorphoses. Physiology in its essence can to-day 

 be no more than cellular. 



These metamorphoses are, as we have said, " changes of 

 form and composition." Changes of composition are not 

 necessary to characterize life, for every organic body in 

 contact with the air will absorb oxygen and evolve carbonic 

 acid, until it may have become burnt up or putrid. The 

 globule, however, far from being destroyed by this change, is 

 transformed, is multiplied. This represents its life. Cuvier 

 defines this " un tourbillon" (vortex), rather an incomplete 

 definition, because, laying aside the changes of form, it can 



