No. 550] 



BREEDING MICE 



ered with galvanized iron, which drains into a sink. By 

 flushing off the top at intervals, the waste is easily dis- 

 posed of. 



While the use of glass in case building may implv an 

 increase in the cost of construction, yet in the above plan 

 it is believed that this cost has been reduced to a mini- 

 mum, and that a case has been provided which in addi- 

 tion to its quality for observation assures unusual con- 

 ditions of sanitation. 



A point of great importance in the construction of 

 such a case is that the galvanized iron back and the side 

 and front glasses rest on the mesh-bottom so that waste 

 material in falling through does not strike the frame- 

 work of the case. It will be seen from a view of the bot- 

 tom (Fig. 4) that the back of the case is bent inward 

 an inch from its base so as to come well out on the mesh 

 bottom, and that the sides and front are placed well over 

 the line of the framework of the bottom. 



2. Nest Boxes and Nesting Materials. — I have followed 

 with satisfactory results the largely used plan of hav- 

 ing a winter and a summer nest box. The winter nest 

 box is made by cutting a chalk box to three-fourths size. 

 This is filled two-thirds full of nesting material. The 

 summer nest is a small sized box similarly furnished. 



Various materials have been tested for nesting, to 

 many of which objections can be made. Cotton although 

 warm, retains odor and at the same time offers a more 

 serious objection in that the young often become en- 

 tangled in it, and are thus permanently injured or even 

 killed. Excelsior I have found to make a good nest if 

 lined with some sort of soft material, as, for example, 

 crude floss. One of the most satisfactory materials 

 which I have tried for nesting is the shredded paper 

 used in the packing of china. If this can not be procured 

 at the china store it mav be prepared by cutting up any 

 kind of soft paper. 



3. Food Receptacles and Food.— I have tried various 

 kinds of food receptacles, most of which have given little 

 or no satisfaction. The difficulty of keeping the food 

 reasonably clean in open food cans is so great that some 



