ADDRESS 



OF 



THOMAS HENRY HUXLEY, LL.D., E.E.S., 



PRESIDENT. 



Mr Lord?, L.vdies, and Gentleitex, 



It has long been tho custom for the newly installed President of the British 

 Association for tho Advancement of Science to take advantage of the elevation 

 of the position in which the suffrages of his colleagues had, for the time, 

 placed him, and, casting his eyes around the horizon of the scientific world, 

 to report to them what could be seen from his watch-tower ; in what direc- 

 tions the multitudinous divisions of the noble army of the improvers of 

 natural knowledge were marching ; what important strongholds of tlie great 

 enemy of us all, Ignorance, had been recently captured ; and, also, with duo 

 impartiality, to mark where the advanced posts of science had been driven 

 in, or a long-continued siege had made no progress. 



I jjropose to endeavour to follow this ancient precedent, in a manner suited 

 to the limitations of my knowledge and of my capacity. I shall not presume to 

 attempt a panoramic survey of the world of Science, nor oven to give a sketch 

 of what is doing in the one great province of Biology, with some portions of 

 which my ordinary occupations render me familiar. But I shall endeavour 

 to put before you the history of the rise and progress of a single biological 

 doctrine ; and I shall try to give some notion of the fruits, both intellectual 

 and practical, which we owe, directly or indirectly, to the working out, by 

 seven generations of patient and laborious investigators, of the thought 

 which arose, more than two centuries ago, in the mind of a sagacious and 

 observant Italian naturalist. 



It is a matter of every day experience that it is difficult to prevent 

 many articles of food from becoming covered with mould ; that fruit, sound 

 enough to aU appearance, often contains grubs at the core ; that meat, left to 

 itself in the air, is apt to putrefy and swarm with maggots. Even ordinary 

 water, if allowed to stand in an ojjen vessel, sooner or later ^becomes turbid 

 and full of living matter. 



The philosophers of antiquity, interrogated as to the cause of these pheno- 

 mena, were provided with a ready and a plausible answer. It did not enter 

 their minds even to doubt that these low forms of life were generated in the 

 matters in which they made their appearance. Lucretius, who had drank 

 deeper of the scientific spirit than any poet of ancient or modern times ex- 



1870. / 



