AQUATIC PLANTS USEFUL TO THE MICROSCOPIST. 53 



infusorian it speedily becomes I'ahguid, its movements 

 cease, and it finally dies, as does every creature that 

 ventures into Utriculdria's utricles, which evidently 

 contain something more than simple water. 



If these bladders are torn to pieces under the micro- 

 scope with the needles, the remains of many kinds of 

 minute creatures will be seen, the soft 

 parts of the captives having been dis- 

 solved, absorbed, and gone to nourish 

 the plant. The whole inner surface of 

 the utricles is lined by innumerable color- 

 less four-parted bodies, one of which is 

 shown much magnified in Fig. lo. They "^ a^ pro7e?s"frot 

 are distinctly visible only when the utri- inner Surface of 

 cle is torn to pieces. They are said to ^"^'=!^°' utri- 

 be the glands which absorb the fluid in 

 which the entrapped animals have been dissolved. 



CERATOPHYLLUM DEMERSUM (Fig. 11). 



This is commoner and more abundant than Myrio- 

 phyllum, for which it is often mistaken, although the 

 two have only a rem.ote general likeness. The leaves 

 of Myriophyllum are fine and soft, those of the Cerato- 

 phyllum rather coarse and stiff. In the latter they 

 are whorled with six to eight in each circle, but 

 instead of being divided on each side down to the mid- 

 dle line (the midrib), as in Myriophyllum, they appear 

 to separate into two narrow parts near the main stem, 

 while each division then often divides into two other 

 parts. Both these arrangements are represented in 

 Fig. II, where the whorl is shown' separated, as was 

 done in Myriophyllum. The leaves always bear several 

 very small but visible spines on their sides, as in the 



