ANIMALS AFTER INOGVLATION. 249 



at the same time its temperature, as indicated by a 

 thermometer placed in the rectum, is to be recorded.' 

 By comparison of these daily observations the ob- 

 server is aided in determining 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 60 or 

 100 grammes in twenty-four hours, even in animals 

 whose total weight may not exceed 500 or 600 gammes; 

 similarly unexplainable rises and falls of temperature, 

 often as much as a degree from one day to another, are 

 seen. Such fluctuations have apparently no bearing 

 upon the general condition of the animal, but are prob- 

 ably due to transient causes, such as overfeeding or 

 scarcity of food, improper feeding, lack of exercise, 

 excitement, fright, etc. 



The accompanying charts (Figs. 50, 51, 52, 53) will 

 serve to illustrate some of these points. The animals, 

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

 from among ^tock 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 thermometer must be inserted into the rectum beyond the 

 grasp of the sphincter, otherwise pressure upon its bulb by contraction 

 of this muscle may force up the mercurial column to a point higher 

 than that resulting from the actual body-temperature. 



