244 Dr John Lowe on Asplcnium germanicum. 



of A. germanicum growing from the same root with A. 

 seytentrionale, but there were unfortunately no inter- 

 mediate forms proviog their common origin, and I w^as 

 unable to bring the roots home in a sufficiently good state 

 to enable me to keep them alive. 



In 1882 I was more fortunate in finding, near the same 

 locality, several other specimens bearing on the same root 

 every intermediate form betwixt A. germanicum and A. 

 septentrionale. A few which are here figured (p. 243) 

 will, I venture to think, help to decide the question. The 

 roots which were brought home are still flourishing, and 

 have put up a goodly crop of fronds, which are all typical 

 forms of A. germanicum. This fact is especially interest- 

 ing when viewed side by side with the instance noted by 

 Mr Boyd, who informs me that his specimen, varying 

 betwixt the two forms, finally developed into A. septen- 

 trionale. 



In the figures which I have given it will be observed 

 that only the intermediate forms are figured, but there 

 were on the same root other fronds, having the distinctive 

 characters of each species. I need scarcely add that 

 extreme care was taken to satisfy myself that there was 

 only a single root, all the fronds being observed to issue 

 from the same point. 



Preliminary Note on the Evolution of Oxygen by Seor- Weeds. 

 By John Eattray, M.A., B.Sc, F.E.S.E., Scottish 

 Marine Station, Gran ton, Edinburgh. 



(Read May 14, 1885.) 



Soon after commenciiig my work on the Algae of the 

 basin of the Firth of Forth in the summer of last year, I 

 observed that living specimens of different species when 

 kept in vessels of water in. the floating laboratory, and 

 exposed to the influence of sunlight, emitted a very variable 

 number of bubbles of gas, though placed as far as possible 

 under similar external conditions. Not being able to 

 discover any data hearing on the fi^oportion of oxygen to the 

 entire quantity of gaseous matter accumulating under such 

 circumstances, I determined to make a series of experi- 

 ments, with the view of finding out whether any variations 



