382 



BIOLOGY OF THE LABORATORY MOUSE 



industry — the animal sits quietly in a corner of the cage, frequently hunched 

 over with his head bent down. His hair becomes ruffled and loses its normal 

 gloss; anorexia develops to a varying degree though usually not complete, 

 and loss of weight occurs. Later, a conjunctivitis may develop, the eyelids 

 become glued together, and the respiratory rate is accelerated. The feces 

 are usually formed, but are softer and lighter in color. A few animals 

 become hyperexcitable shortly before death. The temperature usually 



Table i 

 The Effect of Infection with 5. typhimurium on the Leukocytes 



OF THE Mouse 



* This figure represents the percentage of granulocytes which are immature. 

 Taken from Seiffert, Jahncke, and Arnold (247). 



remains within normal limits, although a terminal rise and fall may occur 

 (247). The blood picture shows a leukopenia with an increase in granulo- 

 cytes, many of which are young forms, and a decrease in lymphocytes (Table 

 i). Increased polychromatophilia and slight poikilocytosis of the erythro- 

 cytes are present. 



In the acute form the disease progresses rapidly and death may occur 

 within a week, the above signs occurring almost simultaneously or in rapid 

 succession. In the chronic form, there may be no signs of illness, or only 

 those of a mild infection followed by apparent recovery, or of a slowly pro- 

 gressive cachexia. The presence of infection can be verified, however, by 

 isolation of the specific organism from feces and organs of the animals months 



