OBSERVATION OF INOCULATED ANIMALS. 197 



feeding;* at the same time its temperature as indi- 

 cated by a thermometer placed in the rectum is to be 

 recorded.^ By the comparison of these daily observa- 

 tions with one another, one is aided in observing the 

 course the infection is taking. 



Too much stress must not, however, be laid upon 

 moderate and sudden daily fluctuations in either tem- 

 perature or weight, as it is a common observation that 

 presumably normal animals when confined in cages and 

 fed regularly often present very striking temporary gains 

 and losses in weight, often amounting to 50 or 100 

 grammes in twenty-four hours, even in animals whose 

 total \mght may not exceed 500 or 600 grammes; 

 similarly they are seen to experience unexplainable rises 

 and falls of temperature, often as much as a degree 

 from one day to another. Such fluctuations have appa- 

 rently no bearing upon the general condition of the 

 animal, but are probably due to transient causes, such 

 as overfeeding or scarcity of food, improper feeding, 

 lack of exercise, excitement, fright, etc. 



The accompanying charts (Figs. 40, 41, 42, 43) will 

 serve to illustrate some of these points. The animals, 

 two rabbits and two guinea-pigs, were taken at random 

 from among the stock animals and placed each in a clean 

 cage, the kind used for animals under experiment, and 

 kept under as good general conditions as possible. For 

 the first week the rabbits received each 100 grammes of 

 green food (cabbage and turnips) daily, and the guinea- 

 pigs 30 grammes each of the same food. During the 

 second week this daily amount of food was doubled ; 



I The thermometer must Be inserted into the rectum beyond the grasp of 

 the sphincter, otherwise pressure upon its bulb by contraction of this muscle 

 may give results higher than the actual body temperature. 



