i6 



Marvels of the Universe 



Photo ia] [/. /. Wnril. 



THE GLANDS OF A BUTTERWORTS LEAF. 



A slice tKrough the thickness of a leaf, very highly mag- 

 nified under the microscope, in order to sho\v how the leaf is 

 studded \vith sensitive glands. 



therefore, good reason for assuming that the complex glands of these carnivorous plants have 

 evolved from more simple absorbent hairs. 



The leaves of the Butterwort are also arranged in rosette fashion, and their upper surfaces are 



covered with tiny glands of two kinds, both of 

 which are so small as to be scarcely visible to 

 the unaided eye. In the section of the leaf 

 shown in the illustration these glands will be 

 seen. The larger ones are elevated on pedicels, 

 while the smaller ones are placed very close to 

 the surface of the leaf. Both kinds of glands 

 secrete a viscid fluid, which, like that of the 

 Sundew, becomes acid in the presence of 

 material containing nitrogen. The Butterwort 

 glands are not, however, movable like those of 

 the Sundew. The captured insect is brought 

 into contact with a large number of the glands 

 by the incurving of the margins of the leaf. 

 In this manner it is slowly pushed towards the 

 centre of the leaf, and this causes a considerable secretion of the digestive fluid, which runs towards 

 the apex of the leaf and often carries the insect with it. If the photograph of the Butterwort is 

 observed, the margins of the leaves will be seen to be incurved and turned downwards at their tips. 



Danvin also made some experiments with 

 this plant and one of the most interesting things 

 which he was able to prove was that it is not 

 only carnivorous, but is also a vegetarian feeder ; 

 for he found that it would digest bits of leaves, 

 poUen from flowers, seeds, etc. 



On the marshy soils of other countries still 

 more striking examples of insect-eating plants 

 may be found. The Venus' Fly-trap, of 

 tropical North America, is one of the most 

 remarkable plants in the world, for, as its name 

 implies, it captures its prey by means of a 

 trap, having no viscid secretion like the Sundew 

 or the Butterwort ; indeed, considering that it 

 is a plant, its movements are most uncanny. 



The curious leaves stand more or less erect 

 and are fringed along their margins with con- 

 spicuous teeth, as the photograph on page 17 

 shows. It wiU also be observed that the lobes 

 of the leaves are held like a half-opened book. 

 Presently a beetle alights upon the footstalk of 

 one of them ; although in alighting and closing 

 to capture alighting insects. j-j-g wings it may vlbrate the leaf considerably, 



yet nothing happens. It travels up and down the leaf stalk and right on the back of the leaf 

 itself, even walking with difficulty amongst the teeth at the margins, and still nothing happens. 

 Then suddenly the beetle disappears from view and we find that the two lobes of the leaf have 

 closed, and that their teeth have interlocked, the beetle being enclosed between the lobes. 



What really happened was that the beetle, in moving over the surface of the leaf, touched one 



Fliolo *.»] [y. J. Ward. 



THE BUTTERWORT. 



An insect-catching plant, common on mountain bogs. Its 

 leaves exude a sticky substance, and then curl their edges over 



