Royal Society. 135 



The science of Vegetable Physiology has at all times presented 

 extraordinary difficulties, and although it has employed the talents 

 and the industry of a great number of philosophers, from the earliest 

 period, little progress has been made in obtaining an exact knowledge 

 of the minute organization of plants, and of the mode in which their 

 functions are exercised, at least, when compared with the great ad- 

 vance which has taken place in the analogous sciences which relate 

 to the comparative anatomy and physiology of animals. 



The structure of vegetables, in consequence of its minuteness and 

 intricacy, is involved in the greatest obscurity ; its investigation re- 

 quires the application of powerful microscopes, and is liable to all the 

 fallacies peculiarly incident to such observations : and the greater 

 part of vegetable physiology being dependent on the full and accurate 

 knowledge of that organization, is exposed to the same causes of un- 

 certainty. But the progress of this department of science has suf- 

 fered less from the want of accurate and sufficiently multiplied ob- 

 servations, than from the absence of a well-compacted and consist- 

 ent theory to connect them together; and it was chiefly with a view 

 to supply this great deficiency that the admirable work of Professor 

 de Candolle was written, which has been selected by the Council as 

 justly entitled to one of the Royal Medals. There is, in fact, no 

 branch of botanical science which has not been greatly benefited 

 by his valuable labours : his Theorie Ele'mentaire de la Botanique and 

 his Organographie Vegetate have made most important additions to our 

 knowledge of descriptive botany, whilst in his Physiologie Ve'g^tale r 

 by a most careful analysis and examination of the influence both of 

 external and internal physical agents upon the organs of plants in 

 the great functions of their nutrition and reproduction, by tracing 

 them throughout the whole course of their operations, and by con- 

 necting their results with the well-known and well-established de- 

 ductions of chemistry and other sciences, he has shown that he is 

 also entitled to claim the rank and distinction of an inductive phi- 

 losopher of a very high order. 



The mention of the name of the second of these distinguished Phi- 

 losophers to whom the Royal Medals for the present year have been 

 adjudged, recalls my attention to the circumstances under which he 

 has recently quitted his home and his country to pursue his labours 

 in another hemisphere. He has devoted himself, as you well know, 

 for many years at least, as much from filial piety as from inclination, 

 to the examination of those remote regions of the universe into which 

 his illustrious father first penetrated, and which he has transmitted to 

 his son as an hereditary possession, with which the name of Hersehel 

 must be associated for all ages. He has subjected the whole sphere 

 of the Heavens within his observation to a repeated and systematic 

 scrutiny. He has determined the position, and described the charac- 

 ter of the most remarkable of the nebula?. He has observed and 

 registered many thousand distances and angles of position of double 

 stars ; and has shown, from the comparison of his own with other 

 observations, that many of them form systems whose variations of po- 

 sition arc subject to invariable laws. He has succeeded, by a happy 

 combination of graphical construction with numerical calculations 



