COMMON OBJECTS WORTH EXAMINING. 301 



great interest. The reddish-brown tufts on the 

 various parts of the body, especially of Anihrinus mu- 

 sedrum, are composed of hairs having a remarkable 

 structure, which the beginner is advised to examine 

 for himself, especially since words cannot adequately 

 describe them. They should be studied in water or in 

 Canada balsam. 



12. LiNG.UAL Ribbons of Mollusks. — The tongue, 

 palate, lingual ribbon, or odontophore (it has received 

 several names) is the organ by which the water-snails 

 rasp off their food from submerged stones and plants. 

 It is a band-like body having many rows of short, 

 variously formed teeth, which, under the microscope, 

 present a beautiful and dazzling appearance. It is 

 situated so that it may be partly protruded- and used 

 as a file, which not only removes the food-particles, 

 but carries them into the mouth. It may be obtained 

 from any of the pond-snails, either by dissecting it out 

 under the microscope with needles — a tedious process, 

 successful in the hands of advanced workers — or after 

 dissolving the soft parts of the snail by boiling the 

 animal in a solution of caustic potassa. Drop the 

 snail into a test-tube containing a small quantity of 

 the solution, and boil uatil all of the soft body has 

 disappeared. When the liquid is cold pour it off' 

 gently, and the lingual ribbon will be found at the 

 bottom usually without trouble, although it is often 

 small and always perfectly transparent. The last few 

 drops may be poured on a slip and examined with a 

 low power, when the lingual ribbon will" probably be 

 SiCen and may be isolated with a needle. The form, 

 size, and arrangement of the teeth vary greatly in the 

 ■different water-snails. To see them is worth all the 



