[47] INSTRUCTIONS FOR COLLECTING MOLLUSKS BALL. 



with a microscope witli objectives ranging from 1 inch to one-eighth inch,, 

 preferably those with a good deal of penetration, showing a large field 

 rather than high magnification; two or three deep, old-fashioned watch 

 glasses and test tubes; some canstic potash, an alcohol lamp, and a 

 pair of spring forceps. 



Extracting the animal from its shell, or simply crushing the latter 

 gently, it is dropped into a test tube containing nearly a tablespoonful 

 of caustic potash which has been allowed to attract the atmospheric 

 moisture until it became liquid. Taking the test tube between the 

 arms of the forceps hold it at the side of the flame of the alcohol lamp 

 until it boils, being careful that it shall boil gently and shall not boil 

 over; which, if held over the flame, it is likely to do. Watch that the 

 animal matter is not thrown by ebullition out of the liquid on to the dry 

 side of the tube. If this happens dislodge it by shaking the tube until 

 the fluid washes down the object. Boil slowly and with patience until 

 all the animal matter appears to be dissolved. Then, first shaking the 

 liquid in tJie tube, pour it out quickly and steadily into a watch glass, 

 replacing it by a little water, with which the tube should be rinsed and 

 then emptied into another watch glass. Take the first watch glass and 

 gently agitate the contents and when they are well stirred up give the 

 glass a rotary motion, but not so violent as to spill the contents. This 

 rotary motion will bring the solid particles in the potash to the center 

 of the watch glass. A sheet of white paper under the watch glasses 

 makes the search for the radula easier. The radula unless it is micro- 

 scopic can usually be recognized by its curved elongated shape and 

 apparently reticulated surface. It may be picked out on the point of a 

 needle and transferred to a watch glass of clean water and washed 

 clean of the potash. If microscopic the watch glass can be put on the 

 stage of the microscope and examined with the 1-inch objective, when 

 the search will usually reveal it. If it does not turn up examine the 

 rinsings in the other watch glass, and lastly the test tube itself. 



Having found the radula it may be laid in a drop of pure water and 

 examined under a cover glass. The live box furnished with most 

 microscopes is most convenient. Transmitted light with a Lieber- 

 kuhn reflector, or aided by a bull's-eye lens focussed above the cover, 

 should be used. 



After the general form and appearance of the radula has been noted 

 and sketched or described, if an accurate knowledge of the teeth is 

 desired, since they lie over one another like shingles on a roof, it is nec- 

 essary to tear the radula up so as to get separate teeth, or rows, or 

 parts of rows in full view. The whole can rarely be seen under one 

 focus. The recurved cusp of the tooth being higher than the base both 

 will not come in focus at the same time. Usually there are both small 

 and large teeth in one series so that much caution is needed to make 

 sure that everything has been seen. 



Sometimes the teeth are very transparent and it is desirable to stain 



