56 MICROSCOPY FOR BEGINNERS. 



two have only a remote general likeness. The leaves of 

 Myriophyllum are fine and soft, those of Ceratophyllum 

 rather coarse and stiff. In the latter they are whorled 

 with six to eight in each circle, but instead of being di- 

 vided on each side down to the middle line (the midrib), 

 as in Myriophyllum, they appear 

 to separate into two narrow parts 

 near the stem, while each division 

 then often divides into two other 

 parts. Both these arrangements are 

 represented in Fig. 11, where the 

 whorl is shown separated, as was 

 Fig. 11. whori of Lcaves^of done in Myriophyllum. The leaves 

 always bear several very small but 

 visible spines on their sides, as in the figure, and when 

 taken from the water they usually do not fall against 

 the stem. 



The plant is found in still, shallow places, growing in 

 thick masses and often considerably branched. It makes 

 an excellent retreat for certain Rotifers and worms, but 

 the leaves are so heavy and stiff that they are not as 

 easily prepared for microscopical examination as are 

 those of Myriophylluin ; they often refuse to lie flat, 

 and thus tilt the cover glass and allow the water to run 

 away. But with neither of these plants will the student 

 try to place an entire whorl in the cell. It is always 

 best to clip off with scissors a part of a single leaf, and 

 examine it for whatever may be attached. Work with 

 the microscope is delicate work, and the smaller the ob- 



