522 GENERAL BIOLOGY 



potassium (one fourth ounce more or less for a pint bottle) 

 in the bottom, covering it with dry sawdust (or other good 

 absorbent) and fastening it in the bottom with several 

 discs of thick blotting paper. Gum the edges of the blot- 

 ting paper discs before pressing them into place. After 

 the gum dries, cork tightly, affix a POISON label, and keep 

 it out of the way of small children. An insect net is a 

 valuable adjunct to the cyanide bottle, but the collecting 

 required for studies 2,3,4, 5, and 59 may all be done with 

 the bottle alone if it be dexterously used. 



Swarms and occasions of special abundance should be 

 taken advantage of by one who has to keep a laboratory 

 supplied. It is often possible to get enough of certain kinds 

 of material to last for years at a few strokes of a net, but the 

 opportunity may be a brief one, and not regularly recurring, 

 as in the autumnal swarming. of the milkweed butterfly. 

 Such studies as no. 41 may seem to demand a lot of prelimi- 

 nary collecting of material; but with the wide range of 

 material allowed, and the remarkable abundance of all of 

 the types, it may, with foresight, be had with remarkably 

 little time and labor spent in getting it together. For 

 example, one can go to the ledges of stone in the bed of 

 almost any rapid creek in early autumn and sweep up in a 

 few minutes enough black-fly larvae to last a laboratory a 

 life time. 



Permanent cultures of the insects needed for study 41, 

 and for some of those of study 48, may be easily main- 

 tained in the laboratory. Meal worms or bean weevils may 

 be raised in a closed bin of shorts or of beans, respectively, 

 needing only the occasional removal of the excess of ani- 

 mals and the renewal of their provender. Mosquitoes and 

 midges and certain mayflies from pools may be raised in 

 covered vessels of rain water. 



