4 6 



Land and Freshwater Animals 



the glass tube from breaking when insects are collected on or around solid objects 

 and in crevices ; H, silk netting which is stretched over the end of the tube and tied 

 with thread sealed with wax in order to prevent it from fraying ; this netting 

 prevents the entrance of dust particles into the tube. 



"The end of the rubber tube G is placed near the objects desired, such as small 

 beetles, shells, or any small specimens, which are then drawn into the main chamber 

 through the glass tube D, by the suction which is created by a sharp inhalation at 

 the end of the rubber tube F. 



"Specimens in the main chamber may be emptied into a cyanide jar by removing 

 the bottom cork C, which is pushed into the tube for only about one-third of its 

 length." 



Fig. 41. — Beamer's aspirator. Courtesy of Ward's Natural Science Establishment, Inc. 



Another form of aspirator (Fig. 41) employing the same principles 

 was devised by Dr. R. H. Beamer of the University of Kansas. 



CAGES AND SHELTER 



In the maintenance of many kinds of aquatic invertebrates a "rearing 

 raft" may prove to be very useful. A floating raft or platform of 

 appropriate size is anchored in water suitable for the purpose. Sus- 

 pended beneath this platform are cages so located and so constructed 

 that they maintain the contained animals in approximately the con- 

 ditions of the native habitat, and make convenient their examination 

 and observation by the investigator. 



One of the most generally useful, most easily constructed, and least 

 expensive of cages is the pillow cage (Fig. 42). It is made from a 

 single square of woven wire cloth by doubling and closely folding two 

 opposite edges to form a cylinder, and then in like manner cross-folding 

 the ends. The folds must be crimped tightly and evenly. A square 

 yard of the cloth quartered makes four cages of the size most commonly 

 used for insects. Cages made from small-wire cloth may be folded with 



