110 



I 



ANNALS OF SCOTTISH NATURAL HISTORY 



counted the number on one piece of stem, and my son (Mr. 

 John Scott) counted the number on other four pieces that 

 had previously been all accurately measured. The minimum 

 size of the utricles included in our enumeration was, as in 

 the former experiments, about the one-twelfth of an inch 

 across the longest diameter. 



TABLE SHOWING THE NUMBER OF UTRICLES ox THE FIVE PIECES OF 



UTRICULARJA STEM. 



The total number of utricles (excluding those under the 

 one-twelfth of an inch across the longest diameter) on the 

 five pieces of stem was 1531, and the total number of these 

 containing organic matter, 1371. If from this latter number 

 we deduct the 7 I utricles as probably containing matter that 

 could not be identified, and multiply the remaining 1300 

 by 5^ (the average number of specimens to each utricle), we 

 get 6825 as the number of organisms captured by the 

 utricles on these five small pieces of stem. 



Should the number of specimens captured, as brought 

 out here, be only approximately correct for the rest of the 

 Utricularia growing in the ponds, and the statistics I 

 have given tend to prove that it may be so, it becomes 

 evident that the number of micro-organisms destroyed in the 

 Gullane ponds during the year by the Utricularia must be 

 very great. 



It was observed, during the examination of the Utricularia 

 stems, that the utricles were proportionally much fewer in 

 number on the lower (or older) portions than on the upper 

 (or younger) portions ; and one of the questions consequently 

 suggested was, Had the utricles on the lower part of the stem 



