1879.] 



Pres Lien ts Ad J res*, 



419 



and climatic changes, and which, more recently has been greatly in- 

 terfered with by the agency of man. The greater portion of the 

 botanical section has been nndertaken by Dr. Js. Bayley Balfour, who 

 himself collected the materials. He estimates the total nnmber of 

 plants found at present in Rodriguez at 470 species, viz. : — 297 

 Phienogams and 1 73 Cryptogams ; and he establishes the remarkable 

 fact that of the Phasnogams not less than 108 are to be regarded as 

 introdnced into the island, and that 189 only are indigenous. Great 

 interest attaches to remains of the extinct cave-fauna of Rodriguez ; 

 and the collection made by Mr. Slater, supplied materials for three 

 papers by Mr. E. Newton, Mr. J. W. Clark, and Dr. Gunther. With 

 reg-ard to Zoology, the marine collections were those to which least 

 interest was attached, as they consisted principally of common forms 

 spread over the whole of the tropical Indian Ocean. On the other 

 hand, our knowledge of the Terrestrial Invertebrates received 

 considerable additions, especially in the Myriopods and Arachnids, 

 Coleoptera and Turbellaria, described by Mr. A. G. Butler, Mr. CO. 

 AVaterhouse, and Mr. G. Gulliver. 



The Papers in General. — The papers presented to the Society, and 

 read at our evening meetings, have been more numerous than in any 

 previous year of our existence, and have during the last twelve months 

 reached a total of 118. Some of them appear to have excited unusual 

 interest among the Fellows and their friends ; for, on more than one 

 occasion our meeting-room was filled to an almost unprecedented 

 degree. 



But, beside the interest attaching to their reading and discussion, 

 the papers themselves have offered some very striking features. It 

 would be as invidious to attempt, as it would be impossible to establish, 

 any general comparison of merit among so varied a collection of 

 memoirs ; but I may still be permitted to take this opportunity of 

 expressing my own impressions of a few which fall, more or less, 

 within my own range of study. 



In purely experimental research, that is, in experiments guided 

 by a clear conception of what was wanted to be done, and exe- 

 cuted with adequate instrumental appliances and with the highest 

 manipulative skill, we cannot but be struck by the assiduity and 

 success with which Mr. Crookes has continued his labours. He has 

 now brought to a termination his remarkable series of papers on 

 Repulsion resulting from Radiation ; and has already struck out into a 

 new region, viz.. the study of certain Electrical Phenomena which 

 appertain especially to high vacua. In the vacua to which he has 

 now turned his attention, the exhaustion has been carried even beyond 

 that in which the phenomona of the Radiometer are produced : and ib 

 is by a legitimate and sagacious step that he has now occupied a com- 

 plete field of inquiry intermediate to the most extreme vacua ever 



