lOO 



INFECTIOUS LEUKAEMIA 



duced, little can be positively stated concerning the early 

 symptoms. There is a pronounced anaemic condition of the 

 mucosa of the head. An examination of the blood shows a 

 marked diminution in the number of red corpuscles and an 

 increase in the number of white ones. In the disease pro- 

 duced artificially by feeding cultures of the specific organism 

 there is, in most cases, a marked drowsiness and general 

 debility manifested from one to four days before death occurs. 

 The period during which the prostration continues varies 

 from a few hours to two days. The mucous membranes and 

 skin about the head become pale. There is an elevation of 

 from I to 4 degrees of temperature. The fever is of a con- 

 tinuous type, as shown in the appended temperature chart of 

 two fowls in which the disease was produced artificially : 



FAHR 



Hi 



III 



I/O 

 101 

 106 



107 



lOh 



/3 



Fig. 15. Temperature chart of tivo cases of infectious leukaemia 

 artificially produced in fowls. 



Although the course of the disease in different fowls is 

 usually constant, there are many variations. The time re- 

 quired for fatal results is from two to three weeks, but ordinarily 

 death occur in about eight days after feeding the cultures. The 

 rise in temperature can be detected about the third day and ex- 

 ternal symptoms about the fifth or sixth, occasionally not until 

 a few hours before death. The symptoms observed in the 

 cases produced by feeding correspond with those described by 

 the owners of affected flocks. 



As indicated in the inoculation experiments, the symp- 

 toms following the intravenous injection of the virus were, as 



