244 DISEASES OF TRUE INFECTION. 



are filled with dark, imperfectly clotted blood. The liver and kid- 

 neys are hypersemic. The spleen is always filled with blood, swol- 

 len, and occasionally streaked with hemorrhagic spots. 



The condition of the brain and spine was formerly supposed to 

 present some reliable indications of the disease, but, according to 

 the investigations of the last few years, it cannot be said that they 

 present any constant pathological alterations. They vary greatly, 

 and in some cases may present nothing at all. We frequently find 

 hyperaemia of the covering of the brain and spinal cord, accom- 

 panied by slight hemorrhages, and the brain and spinal matter 

 itself contains more blood than usual and is in a more or less 

 cedematous condition. 



Kolesnikoff found on microscopic examination of the walls and 

 neighboring vessels of the brain (of dogs which have died with 

 rabies) an accumulation of lymphoid cells and extravasated red 

 blood-corpuscles. Wassilieff observed also dull masses which were 

 considered by Weller as peculiar fatty bodies present in rabies, 

 while Czokor and others have demonstrated that these corpuscles 

 are products of involution which are .found in other animals in the 

 normal state. He also found that these were entirely absent in 

 the early stages of rabies. The accumulation of discolored cells 

 and red corpuscles in the walls and perivascular chambers of the 

 small bloodvessels indicates to a certain extent a condition which 

 in rabies is of pathological importance. They are undoubtedly 

 symptoms of inflammation. These changes vary in different cases. 

 According to Czokor, it was noticed to a very slight degree in 

 dogs affected with the furious form of rabies, but it was noticed 

 to a marked degree as soon as the disease developed the dumb 

 form (the perivascular spaces and their neighborhood were filled 

 with leucocytes). Similar alterations have been noticed in other 

 diseased conditions, such as chorea, tetanus, and meningitis. 



Clinical Symptoms and Course. The period of incubation 

 lasts in the majority of cases from three to five weeks. In very 

 rare instances the disease may appear in one week. According to 

 Haubner's observations upon nearly 200 dogs, in 83 per cent, of 

 the cases the disease developed in two months; in 16 per cent, of 

 the cases within three months ; and in 1 per cent, four months, or 

 even later. Ziindel has calculated that in 264 dogs 1 per cent, 

 became affected within twenty-four hours after being bitten; 11 



