136 BACTERIOLOGY 



cages. Very large animals, such as monkeys and dogs, require 

 specially constructed cages. Laboratory animals should receive 

 very careful attention. They should be supplied with new food 

 at least once daily and with clean water twice a day. If food 

 remains at the end of the day, it should be removed and a smaller 

 amount given for the next day. The cages should be completely 

 emptied and cleaned at least once a week, the refuse being in- 

 cinerated. The animal house should be screened, and insects of 

 all kinds given careful attention. It will be found practically 

 impossible to control the lice and fleas, but winged insects, es- 

 pecially biting varieties, may be kept out; and bedbugs, which 

 sometimes gain entrance on new lots of guinea-pigs or rats, should 

 not be allowed to remain uncontrolled. These possible carriers 

 of infection require serious consideration as sources of confusion 

 where experimental investigations are being carried out, not to 

 mention the element of danger to the human individuals in the 

 neighborhood. 



Holding for Operation.— Animals to be inoculated or operated 

 upon must be held in a fixed position. Many special mechanical 

 holders have been devised for the various animals, but these 

 are not necessary or especially useful. A pair of long-handled 

 hemostatic forceps with lock, or a pair of placental forceps with 

 lock, will be found most serviceable in handUng mice or rats, 

 the loose skin of the animal's neck being caught in the forceps. 

 Guinea pigs are best held by an assistant, the thumb and fore- 

 finger of one hand encircHng the thorax just behind the fore legs 

 and the other hand holding the hind legs stretched out. Rabbits 

 are held by the ears and hind legs with the body stretched over 

 the knee. Monkeys are to be handled with thick gloves and 

 should be caught around the neck from behind with one hand and 

 by the pelvis or hind legs with the other. A second assistant 

 is required to hold the fore legs. For all work which would cause 

 any considerable pain the animal must be anesthetized, either 

 by putting it into a closed compartment with the anesthetic or 

 by use of a cone. Anesthesia is also necessary when delicate 



