852 REPORT — 1895. 



FRIDAY, SEPTEMBER 13. 



The following Papers were read : — 



1. Experimental Studies in the Variation of Yeast Cells. 



By Dr. Emil Chr. Hanskn, Copenhagen. 



The author gave an account of his earlier and more recent investigations. 

 Among the latter he especially dwelt on those in which, by one treatment, varieties- 

 were produced that gave more, and by another treatment less, alcohol than their 

 parent cells. He pointed out that the observed variations could be grouped under 

 certain rules. From his researches on the agencies and causes to which variatiork 

 is due he found that temperature was the most influential external factor.' 



2. On a New Form of Fructification in Sphenophyllum. 



By Graf Solms-Laubach, Strasshurg. 



Graf Solms gave a brief sketch of the history of our knowledge of the fructifi- 

 cation of the Carboniferous genus Sphenophyllum. He described the type of 

 strobilus orio-inally named by Williamson Volkmannia Dmcsoni, and subsequently 

 placed by Weiss in the genus Bowmanites ; this fructification has recently been 

 shown by Williamson and Zeiller to belong to Sphenophyllum. The author pro- 

 ceeded to give an account of a new form of strobilus recently obtained from rocks 

 of Culm ao'e in Silesia ; this shows certain important deviations from the fructifi- 

 cations previously examined. In the Sphenophyllum strobili from the Coal- 

 measures the axis bears successive verticils of coherent bracts, the sporangia are 

 borne singly at the end of long pedicils twice as numerous as the bracts, and 

 arising from the upper surface of the coherent disc near the axil. In the Culm 

 species, Sphenophyllum Romeri, sp. nov., the bracts of successive whorls are super- 

 posed and not alternate, as described by other writers, in the Coal-measure species j 

 a more important feature of the new form is the occurrence of two sporangia 

 instead of one in each sporangiophore or pedicil. 



Graf Solms referred to the unique collection of microscopic preparations of 

 fossil plants left by Professor Williamson ; he emphasised in the strongest terma 

 the immense importance of the collection, and pointed out how every worker in 

 the field of Palseozoic botany must constantly consult the invaluable type specimens 

 in the Williamson cabinets. 



3 The Chief Eesults of Williamson^ s Work on the Carloniferous Plants. 

 By Dr. D. H. Scott, F.R.S. 



The origin and history of the late Professor Williamson's researches on the 

 Carboniferous flora were briefly traced. His great work, chiefly, though not 

 entirely, contained in his long series of memoirs in the 'Philosophical Transactions' 

 of the Royal Society, consisted in thoroughly elucidating the structure of British 

 fossil plants of the coal period, and thus determining, on a sound basis, the main 

 lines of their aflinities. 



Four of the principal types investigated by Williamson were selected for illus- 

 tration — the Calamariece, the Sphenophyllece, the Lyginodendrecs, and the Lycopo- 

 diacece. 



(1) The Calamnrieo!. — Williamson's great aim, which he kept in view all 

 through, was to demonstrate the essential unity of type of the British Calamites, 

 i.e. that they are all Cryptogams, of equisetaceous affinities (though sometimes 

 heterosporous), both possessing precisely the same mode of growth in thickness by 

 means of a cambium, which is now characteristic of Dicotyledons and Gymnosperms. 



' For a fuller account of Dr. Hansen's work, sec the Annals of Botany, 1895. 



