ON THE FOOD OF UTR1CULAR1A VULGAR1S in 



fallen off by reason of the disorganisation of their tissues 

 from their having become gorged with animal matter, or had 

 they fallen off as the result of normal development similar 

 to that which causes the leaves of trees, etc., to fall in the 

 autumn ? A second question suggested was, If becoming 

 gorged with animal matter does not injure the utricles and 

 cause them to fall off, is the animal matter they contain 

 gradually, and more or less continuously, assimilated by the 

 plant, so that the utricles remain more or less permanently 

 active and able to go on adding fresh captures to those 

 previously made ? I find no satisfactory evidence bearing 

 on these questions. 



Darwin's investigations certainly proved that animal 

 matter is absorbed by the quadrifid processes that so 

 thickly beset the internal surface of the utricles ; but whether 

 they can continue for a lengthened period to absorb such 

 matter as it would be necessary for them to do if the utricles 

 are to remain active and capable of adding to their captures, 

 is still doubtful. My own opinion is that the utricles, after 

 becoming gorged with animal matter, gradually decay and 

 fall off. ' 



From what has been said above, it is clear that Utricularia 

 growing in any quantity in ponds must be a formidable 

 enemy to the smaller active organisms living in the same 

 water. A tow-net examination of the pond-water of Gullane, 

 from which the Utricularia were taken, shows that while 

 almost all such organisms may be occasionally captured, 

 certain of them fall a prey to the Utricularia-traps in far 

 greater proportion than others. Cypris is the most abundant 

 in both lots of utricles examined, while Cyclops comes next. 

 It seems that the proportion in which the different organisms 

 are captured by the utricles depends to a large extent upon 

 peculiarities in their structure or shape. For instance, it 

 will be observed that, among the Cyclops captured, there is 

 a far larger number of males than females. The statistics 

 given above show that the number of organisms in the two 

 lots of utricles examined (which together amounted to 800) 

 was 3544. Of this number 897 were Cyclops, and comprised 

 799 males, 61 females, and 37 doubtful ; or, in other words, 

 over 89 per cent were males, while less than 7 per cent were 



