Fig. 42. — A pillow cage. 



Cages and Shelter 47 



the fingers but larger and stronger ones will require a small tinker's 

 folding tongs. A woven edge should form the top, so that there be no 

 wire ends to prick the fingers on opening and closing the cage. 



Such a cage is very adaptable. It may be used for carrying home a 

 catch, since its walls afford a foothold, and its crevices at the ends afford 

 hiding places. It may be hung in 

 a tree or buried under trash or im- 

 mersed in a pond, to hold hiber- 

 nating animals in safety from 

 their predatory enemies. It may 

 be used for distributing parasitic 

 insects in a grove by placing para- 

 sitized pupae within it and hang- 

 ing it in a tree; the mesh will then 

 have to be of a size to permit the 

 escape of the parasites, while re- 

 taining their injurious host insects. 

 When rearing the insects that feed 

 on a growing plant one end may be 

 fitted over a flower pot contain- 

 ing the plant. 



When used as a transformation cage for aquatic insects such as 

 dragonflies, stoneflies, and mayflies, it should be set aslant in the water 

 with only the lower end immersed and plenty of room above for ex- 

 panding wings. If any adults chance to fall back into the water, the 

 sloping sides will facilitate their crawling out again. 



Hollow-ground slides capped with a cover glass are often used as 

 rearing cages for organisms of microscopic size. Dr. Marshall Hertig 

 (Science 83: no, 1936) has suggested a method of making them in any 

 desired shape or size. 



"The essential apparatus for turning out these laboratory-made slides is an 

 electric motor (that of an electric fan will serve), a flexible shaft provided with a 

 chuck or "handpiece" into which may be fitted any of the dentist's arsenal of 

 burrs, drills and abrasive devices. Of these the most generally satisfactory for 

 grinding glass are the abrasive wheels, which consist of small disks of carborundum 

 or other material mounted on a mandrel, and which are available in a variety of 

 diameters, thicknesses and degrees of abrasiveness. Abrasive "points," i.e., small 

 carborundum spheres, cones and cylinders, may also be used, but are much less rapid 

 than the abrasive wheels on account of their small diameter and hence low velocity 

 of grinding surface. 



"The process of grinding a depression consists merely of placing a drop of water 

 on the slide and applying the abrasive instrument. Very little spattering occurs. 

 The most rapidly ground depression is the slot made by the edge of the carborundum 

 wheel. A cavity of this shape is desirable for elongate specimens. By moving the 

 wheel while grinding, a depression of almost any size and shape may be made, and 



