74< The President's Address. 



man must, for the present, hold that the operations by which 

 changes arc effected in substances by hving matter are in 

 their nature essentially different from those which man is 

 about to employ to bring about changes of a similar kind out 

 of the body ; and until we are taught what the agent or 

 operator in the living matter really is, it is better to call it 

 vital power than to deny its existence altogether." 



I am not aAvare of a better expression of the other side 

 of the controversy than a passage from M. Berthelot.* 

 M. Berthelot observes that ''the general problems of the 

 nutrition of living beings are chemical problems, and so are 

 those of respiration. The study of these problems rests 

 upon data supplied by organic chemistry. In animal tissues, 

 as soon as the solids, the liquids, and the gases are brought 

 into reciprocal contact, under the influence of movements 

 which are referable to the nervous system and to a special 

 structure, which we do not know how to imitate, purely 

 chemical affinities develop themselves amongst these solids, 

 gases, and liquids, and the combinations to which they give 

 rise depend exclusively on the laws of organic chemistry." 



In another place M. Berthelot affirms that " synthesis con- 

 ducts us to this fundamental truth, that the chemical forces 

 which rule over organic matter are really, and without re- 

 serve, the same as those which rule over mineral matter." 



It is evident that while chemistry may do much to solve 

 questions of this descrixJtion, the microscope is an essential 

 instrument in their investigations, for without it the student 

 would be utterly unable to understand the character of the 

 apparatus which nature employs in living beings, and the 

 chemist himself would be in constant danger of treating as 

 homogeneous wholes portions of matter which the micro- 

 scopist can demonstrate to consist of separate and dissimilar 

 materials. 



I will only further allude to Dr. Beale's paper for the sake 

 of observing that it contains important reasons for regarding 

 the materials contained in the serum of the blood as the 

 pabulum of the tissues. 



At the same meeting at which the j)aper on Nutrition was 

 read. Dr. Beale made a brief communication to meet an 

 objection made by Dr. Ransom to his i:)lan of staining tissues 

 with carmine, on the alleged ground that the ammonia 

 present in the solution rapidly dissolved the germinal vesicle 

 and contents of the Ovarian ova of a stickleback. 



Dr. Beale explains that there must have been some 



* ' Lefons sur les Methodes Generales de Synthese en Chemie Orffauioue.' 

 By M. Berthelot. p. 9, 



