DOCTRINE OF CONTAGIUM VIVUM. 171 



fever. [Pigs are known to be liable to take splenic fever.] 

 There exists, however, a marked difference between the two 

 diseases in the incubation period, the general pathology,^ 

 and especially in the anatomical character of the spleen and 

 blood. In splenic fever we find the spleen invariably en- 

 larged, being the principal organ of the affection, whereas 

 in pneumo-enteritis it is only occasionally changed. And, 

 likewise, the blood presents entirely different characters in 

 the two diseases; in pneumo-enteritis it is not different in 

 any marked degree from normal blood, whereas in splenic 

 fever it is of dark colour — laky, and does not coagulate at 

 all, or only imperfectly so. Besides, the blood in splenic 

 fever contains the now famous Bacillus anthracis, and 

 hence its conspicuous infectious property, whereas in 

 pneumo-enteritis the fresh blood does not, as a rule, contain 

 any foreign matter, and in most instances does not possess 

 any infectious property. 



Another disease with which pneumo-enteritis bears a 

 great resemblance on account of certain anatomical cha- 

 racters, viz. inflammation of serous membranes, lung, intes- 

 tine, and lymphatic glands, haemorrhage in lung, serous 

 membranes, endocard, muscle of heart, intestinal mucous 

 membrane, and other organs — is specific septicaemia.^ 



The resemblance, however, is not greater than to splenic 

 fever, although the differences are not less well defined. 

 Besides others, there is this great distinction, that in 

 pneumo-enteritis the contagion spreads by simple cohabita- 

 tion and through th air, which it never does in septicaemia, 

 as in this the virus always requires a broken surface through 

 which to enter a healthy individual. Pneumo-enteritis is 

 occasionally described as malignant erysipelas (mal rouge, 

 red soldier), but this is in so far inadmissible, as the affec- 

 tion of the- skin in the former is a very inconstant symptom, 

 and in milder forms of the disease is invariably absent. 

 More recently the pneumo-enteritis has been regarded as 

 tphoid fever of the pig. From a purely anatomical point of 

 view the resemblance between real, i.e. human, typhoid 

 fever and pneumo-enteritis is very slight indeed, so slight, 

 in fact, that to mention it requires a total oversight of some 



1 In splenic fever the period of incubation ranges from between a few 

 hours to several days, in pneumo-enteritis it varies from two to five days 

 and more. Splenic fever is easily transmissible to man and the domestic 

 animals, whereas the transmissibility of the pneumo-enteritis is much 

 more limited. Hitherto I have succeeded in communicating it to rabbits. 

 Guinea-pigs and mice, although only with difficulty. 



2 Specific septicaemia as distinct from septic infection. See Dr. Burdon- 

 Sanderson's lectures at the University of London, 1877. 



