196 BACTERIOLOGY. 



allowed to remain, and where its pathogenic properties 

 upon the iris can be conveniently studied. It is a mode 

 of inoculation of very limited application, and is there- 

 fore but rarely practised. It was employed by Cohnheim 

 in demonstrating the infectious nature of tuberculous 

 tissues, tuberculosis of the iris being the constant result 

 of the introduction of tuberculous tissue into the 

 anterior chamber of the eye of rabbits. 



OBSEEVATIOJSr OF ANIMALS AFTER INOCULATION. 



After either of these methods of inoculation, particu- 

 larly when unknown species of bacteria are being 

 tested, the animal is to be kept under constant observa- 

 tion and all that is unusual in its conduct noted — as, for 

 instance, elevation of temperature ; loss of weight ; pecu- 

 liar position in its cage ; loss of appetite ; roughening 

 of the hair ; excessive secretions, either from the air- 

 passages, conjunctiva, or kidneys ; looseness of or hemor- 

 rhage from the bowels ; tumefaction or reaction at site of 

 inoculation, etc. If death ensues in from two to four 

 days it may reasonably be expected that at autopsy 

 evidence of either acute septic or toxic processes will 

 be found. It sometimes occurs, however, that inocula- 

 tion results in the production of chronic conditions, and 

 the animal must be kept under observation, often for 

 weeks. In these cases it is important to note the pro- 

 gressive changes that are in progress by their efPect 

 upon the physical conditions of the animal, viz., upon the 

 nutritive processes as evidenced by fluctuation in weight 

 and upon the body temperature. For this purpose the 

 animal is to be weighed daily, always at about the same 

 hour and" always about midway between the hours of 



