TRANSACTIONS OF SECTION K. 573 



not easily distinguishable. Four loop-shaped chromosomes are present. Their 

 behaviour on the spindle appears to be normal. Spindle-fibres, few in number, 

 have been observed. 



It is difficult to determine how many divisions precede spore formation. The 

 spindle-figures of the first division are relatively larger than those of the suc- 

 ceeding divisions. The nucleolus persists and divides during anaphase to form 

 two daughter nucleoli. The spindle-figures of the last division (that immediately 

 preceding spore formation) are exceedingly small. 



Nuclear division within the spore has not been observed. 



11. Preliminary Note on an Investigation of some West African Fungi. 

 By A. Eckley Lechmere, M.Sc. 



^ A series of cultures made from fungi collected in the Virgin Forest of the 

 Cote d'lvoire (French Congo) have yielded some interesting forms. Amongst 

 others a series of three forms have been isolated, showing a life-history of 

 great interest. Each of these shows the formation of distinct perithecia contain- 

 ing numerous asci with eight ascospores. When quite ripe dehiscence takes 

 place by means of emission of a long thread-like mass of ascospores from an 

 irregular terminal pore exactly recalling the emission of sporidia in certain genera 

 of the Sphseriaceas, in other characters these species closely resemble the group 

 Perisporiaceae. The three forms, although exactly comparable as regards their 

 perithecia and asci, differ considerably as regards their asexual form of repro- 

 duction. 



The first form ' L 2 ' has no other form of reproduction except the perithecia. 

 The second form 'A' shows a plentiful production of 'oidial' cells in the 

 mycelial filaments to such an extent that after a week's growth the whole 

 mycelium is completely black. The third form 'B' shows the formation of 

 conidia of the ' Coramium ' type. 



All attempts to get a transition from one form to the other have been so 

 far unsuccessful, the three forms remaining true to their characters in pure 

 culture. 



As to the position of these fungi, it is not yet possible to classify them with any 

 accuracy ; they seem at any rate to belong to a new genus, and occupy a position 

 in the Pyrenomycetes somewhere between the groups Perisporiaceas and 

 Sphoeriaceas. 



MONDAY, SEPTEMBER 4. 



Joint Discussion with Sections C and E on the Relation of the present 

 Plant Population of the British Isles to the Glacial Period. Opened 

 by Clement Reid, F.R.S. 



The distribution of our British plants has long been a puzzle to the botanist, 

 and no explanation was forthcoming till the cause was searched for in bygone 

 changes of climate, and changes in the distribution of land and sea. A cen- 

 tury ago it was generally supposed that species had originated mainly in the 

 districts in which they were then found. But even under this hypothesis the 

 anomalies of discontinuous areas seemed to require explanation, for the same 

 species was not likely to originate at several different points. 



With the growth of the idea of gradual evolution it was realised that faunas 

 and floras had a past history, even if the included species had remained un- 

 changed. Botanists recognised that there were many points that required ex- 

 planation. For instance, it was noticed at an early date that each of our moun- 

 tain-tops possessed a small outlying fragment of the arctic flora. How came 

 it that the same species occupied so many different mountains ? This seemed a 

 perfectly fair subject of inquiry, even to naturalists who hated the very idea of 

 evolution when applied to species and genera. 



