I860.] Proceedings of the Asiatic Society of Bengal. 83 



These might be procured partly in this country and partly in 

 China. 



I have, &c, 



(Sd.) W. S. Atkinson, 

 Secretary, Asiatic Society. 



Mr. R. Jones previously to giving a microscopic demonstration of 

 Diatomacese offered a few remarks descriptive of these organisms. 

 They were described as a family of confervoid Algaa differing from 

 other unicellular Alga?, in being furnished with an external coating of 

 silex. The method of determining the structure of the Diatomaceous 

 frustule was explained, and attention was directed to the singular 

 beauty of the traceries and markings exhibited by the silicious 

 valves and to the difficulty of making out their true condition. 

 The mode of increase of the cells was stated to be, like that of 

 all vegetable cells, a process of division — the only other mode of 

 reproduction known certainly to exist in this class, being that in 

 which the operation of conjugation takes place. It was remarked 

 however that these phenomena required for their satisfactory demon- 

 stration quiet and a happy concurrence of other circumstances. It was 

 further stated that the reproduction of Diatomacese, by the break- 

 ing up of the Endochrome into Gonidia, was doubtful. Various causes 

 were mentioned as having been assigned to account for the motion 

 observable in these organisms ; but it was added that, our know- 

 ledge on this point was still very imperfect. The habitats of the 

 Diatomaceaj were described, and numerous fossil specimens from the 

 Himalayas, the Arctic regions, America, and various other localities, 

 were exhibited during the evening ; and it was mentioned, as an in- 

 teresting fact, that the same species were found under conditions widely 

 differing, and in places distantly remote from each other. 



Dr. Crozier remarked that the description of the organization of 

 the Diatomaeeaj with which Mr. Jones had so ably favoured the meet- 

 ing and the microscopic demonstrations which would now be given of 

 them, both recent and fossil, were very interesting, especially as these 

 minute organized beings have only very lately been brought to our 

 knowledge by the valuable assistance our sense of sight receives from 

 the compound achromatic microscope ; and they were, though invisi- 

 ble to the naked eye, found wherever there is fresh or salt water— in 



m 2 



