90 Mr Burkill, On a collection of Plants [Feb. 10, 



With Hottonia the few experiments we made were more satis- 

 factory. 



Aug. 1. Old Tap- water. 



still 23 p.c. oxygen 

 stirred 22 „ „ 



Aug. 2. Old Tap-water. 



still 23 

 stirred 23 



In the case of Potamogeton the results were conflicting, but on 

 striking an average it was clear that no marked effect on the 

 percentage of oxygen was produced by stirring. 



It is worth noting that the percentage of oxygen yielded by 

 Potamogeton is always much higher than that given by Elodea or 

 Hottonia, being occasionally as high as 58 per cent. We are 

 unable to suggest a reason for this difference. For Elodea and 

 Hottonia the case stands thus : stirring does not seem markedly 

 to affect the percentage of oxygen, while it increases the yield of 

 gas. If so, the total amount of free oxygen yielded must be 

 increased, and this probably implies increased assimilation. 



Although the evidence from gas analysis is not conclusive, we 

 have shown by a direct evidence that assimilation is increased by 

 movement of the water. 



This was proved to be the case by cultivating water-plants 

 in still and running water, and observing, by means of Sachs' 

 iodine-test, the relative amounts of starch produced. The plants 

 were de-starched by darkness before being used for the experi- 

 ment, and care was taken to ensure identity of temperature and 

 illumination. Two trials were made with Elodea and one with 

 Potamogeton, with identical results ; namely, that all the specimens 

 from the running water contained distinctly more starch than those 

 from the still water. 



(4) On a collection of plants from New Britain {Neu Pommern). 

 By I. H. Burkill, M.A., Gonville and Caius College. 



In 1875 Baron A. von Htigel visited several islands in the 

 Pacific, and brought back collections of plants from Ovalau in the 

 Fiji group, Upolu in the Samoa group, from the Duke of York's 

 Island (New Lauenburg), and from New Britain. The last-named 

 island he was unable to visit in person, and had, therefore, to 

 entrust the collecting entirely to his collector. Unfortunately a 

 number of accidents caused the loss of a large part of the 

 collections, and the remaining material only represents a portion 

 of what had been obtained. These collections were subsequently 

 presented to the University Herbarium. 



