158 THE KEEPING OF ANIMALS 



each direction than the cage. To clean, it is only necessary to lift the cage 

 off the tray. It is an advantage to have two trays for each cage so that one 

 may be disinfected and dried while the other is in use.] 



The cages must be cleaned daily, and should an animal die or be removed 

 to make room for a new occupant the cage in which it lived must be dipped 

 in some strong antiseptic solution (phenol, lysol) or be sterilized 

 by flaming it with spirit or with a large specially constructed gas 

 burner (fig. 130). 



Each cage should carry a label indicating the nature of the 

 experiment, and the day upon which the animal was inoculated. 

 (i) Rabbits, guinea-pigs, rats and mice. Rabbits and guinea-pigs 

 can be conveniently kept in the cages described above. 



Grey rats [Mus decumanus], as well as house [Mus musculus] 

 and field [Mus silvaticus] mice should, as a rule, be caged singly. 

 When several of these rodents are put in one cage they fight, and 

 frequently kill each other. They are best kept in large wide- 

 mouthed jars, the mouth being covered with metal gauze fastened 

 down round the neck with iron wire. 



White rats are frequently very tame, and can be kept in small- 

 FIG 130 mesn wire-netting cages or bird cages, or even in wooden boxes fitted 

 Gas IG buriier with a wire-netting door. 



ca, r e? aming White mice should be kept in glass jars or metal boxes such as 

 Palmer's biscuit boxes, the lid of which must be pierced with a 

 number of holes. The floors of the boxes or jars, whichever be used, should 

 be covered with a layer of sawdust several centimetres deep, and a little wool 

 should also be put in the cage as mice do not like the cold.. 



There is no need here to discuss the proper feeding of rabbits, guinea- 

 pigs, etc. 



Mice and rats should be fed on corn and moistened bread. White rats 

 are very fond of water, and a small dish containing it should, therefore, be 

 put in their cages. 



(ii) Monkeys. Monkeys require a great deal of attention. Their cages must 

 be large and be kept scrupulously clean. They are very susceptible to the 

 cold, and the house in which they are kept ought, in these climates, to be artifi- 

 cially heated most of the year. The nature of the food required varies with 

 the different species, but, generally speaking, milk, 1 dried fruits, [cooked rice], 

 bananas and bread constitute the staple articles of diet of monkeys in cap- 

 tivity. They should be given something to drink twice a day, but it is 

 advisable not to leave water [or milk] in their cages. 



(iii) Frogs. Frogs can be easily kept at ordinary room temperatures, but 

 at temperatures approximating to that of the human body, such as are 

 sometimes necessary under experimental conditions, they often die in a day 

 or two without any apparent reason. 



Ledoux-Lebard suggests the following as a useful method for keeping frogs (Rana 

 esculenta is better than Rana temporaria) at a temperature of 35 or 37 C. for a 

 month or more. Keep each frog in a bottle containing a few centimetres of water 

 and covered with a piece of stout muslin tied on with string, renew the water daily 

 with a fresh supply at the same temperature, and cram the frog once a week with 

 beef, veal or mud worms. 



Isolation of inoculated animals. Inoculated animals must, of course, be 

 rigidly kept away from the neighbourhood of normal animals. 



[ x It must not be forgotten that monkeys and apes are highly susceptible to tuberculosis, 

 so that the milk must either come from an unimpeachable source or be sterilized before 

 being fed to them.] 



