AQUATIC PLANTS USEFUL TO THE MICROSCOPIST. 55 



head inside tlie utricle, and firmly held by the pressure 

 of the valve. In these cases, however, it seems proba- 

 ble that the struggles of the dying fish may have wedged 

 it fast, rather than that the valve has held it. Small 

 worms and worm-like larvae have been found half in and 

 half out of these fatal traps, for once past the curtain- 

 like valve the little animal never escapes. ,And no 

 sooner has it entered than it begins to show signs of 

 discomfort ; if it has a shell it withdraws its legs and 

 head and closes the shell ; if a worm or animalcule it 

 speedily becomes languid, its movements cease, and it 

 finally dies, as does every creature that ventures into 

 Utricularia's utricles, which evidently contain something 

 more than simple water. If these bladders are torn to 

 pieces under the microscope with the 

 needles, the remains of many kinds of 

 minute creatures will be seen, the soft 

 parts of the captives having been dissolved 

 and absorbed, and gone to nourish the Fi tT 10 _ 

 plant The whole inner surface of the fid Process n-om 



. ,. , , . Inner Surface of 



utricles is lined by innumerable colorless utricle of utri- 

 four-parted bodies, one of which is shown 

 much magnified in Fig. 10. They are distinctly visible 

 only when the utricle is torn to pieces. They are said to 

 absorb the fluid in which the entrapped animals are dis- 

 solved. 



CERATOPHYLLUM DEMERSUM (Fig. 11). 



This is commoner and more abundant than Myrio- 

 phyllum, for which it is often mistaken, although the 



