No. 2.] BRITISH ASSOCIATION MEETING. 155 



not as yet yielded to the iDgenuity of chemical artifice ; nor, in- 

 deed, is the actual composition of one of the most important of 

 these, albumen and its allies, fully known. But as chemists have 

 only recently began to discover the track by which they may be 

 led to the synthesis of organic compounds, it is warrantable to 

 hope that ere long cellulose and lignine may be found ; and, great 

 as the difficulties with regard to the albumenoid compounds may 

 at present appear, the synthetic formation of these is by no means 

 to be despaired of, but, on the contrary, may with confidence be 

 expected to crown their efforts. From all recent research, it ap- 

 pears to result that the general nature of the properties belonging 

 to the products of animal and vegetable life, can no longer be 

 regarded as different from those of minerals, in so far at least as 

 they are the subject of chemical investigation. The union of 

 elements and their separation, whether occurring in an animal, a 

 vegetable or a mineral body, must be looked upon as dependent 

 on innate powers or properties belonging to the elements themselves ; 

 and the phenomena of change of composition of organic bodies 

 occurring in the living state are not the less chemical because they 

 are different from those observed in ors-anic nature. All chemical 

 actions are liable to vary according to the conditions in which they 

 occur, and many instances might be adduced of most remarkable 

 variations of this kind, observed in the chemistry of dead bodies 

 from very slight changes of electrical, calorific, mechanical, and 

 other conditions. But because these conditions are infinitely more 

 complex and far less known in living bodies, it is not necessary 

 to look upon the actions as essentially of a different kind, to have 

 recourse to the hypothesis of vital affinities, and still less to shelter 

 ourselves under the slim curtain of ignorance implied in the ex- 

 planation of the most varied chemical pheuomena by the influence 

 of a vital principle. 



EVOLUTION OF SPECIES. 



On the subjects of zoological and botanical classification and 

 anthropology, it would be out of place for me now to make any 

 observations at length. I will only remark, in regard to the first, 

 that the period now under review has witnessed a very great mo- 

 dification in the aspect which the affinities of the bodies belong- 

 iuir to these two ^reat kingdoms of nature bear to each other, 

 and the principles on which in each groups of bodies are associa- 

 ted together in classification ; for, in the first place, the older 



