INTERNAL DISEASES 395 



acute rheumatism, pneumococci, meningococci and streptococci 

 occur as well as staphylococci, while some observers describe a 

 micrococcus rheumaticus as the precise causal agent of acute 

 rheumatism. Besides man, cows, and less frequently, dogs, goats, 

 pigs and horses, may be spontaneously attacked. 



Septic and pyaemic arthritis are frequently seen in calves 

 and foals. Experimentally, the usual laboratory animals are 

 all susceptible. 



Meningitis, which has recently again become epidemic, is due, 

 like acute rheumatism, not merely to one micro-organism, but to 

 many. Recent investigations point to the meningococcus and 

 the pneumococcus as the most frequent cause of meningitis in 

 man, horses, sheep, cattle, goats and dogs. Naturally occurring 

 cases are usually produced by the meningococcus, but, curiously 

 enough, mice and guinea-pigs do not die under experimental 

 conditions unless this organism is injected into the peritoneal 

 cavity, and other animals appear to be quite insusceptible (Marx). 



Dysentery is among the diseases the pathological appearances 

 of which may be produced by more than one micro-organism. 

 The amoeba discovered by Losch and a bacillus may both 

 produce this disease (Plate V., figs. 9 and 10). Dysentery is a 

 disease peculiar to man, spontaneous cases not having hitherto 

 been observed in animals ; it is only after the injection of very 

 large quantities of amoebae, or bacilli, that the characteristic 

 lesions can be produced in the large intestine of cats, rabbits, 

 guinea-pigs and mice. 



Venereal diseases are also peculiar to man. No spontaneous 

 cases of gonorrhoea, soft sores or lues have been observed in 

 animals. Experimental inoculation of cultures of gonococcus in 

 animals produces suppuration in the mucous membranes but 

 no true gonorrhoea (Plate V., fig. n). In 1902 Marx declared 

 that all attempts at inoculating lues into animals (even monkeys) 

 had ended in failure. Since then, however, other results have 

 been obtained. At the fifth International Congress of Dermato- 

 logy in 1904 Van Niessen mentioned pure cultures with which 

 he stated that he had produced symptoms analogous to those of 

 human syphilis in monkeys, pigs and horses. 1 Quite recently 



1 Confirmed by Finger und Landsteiner, " Untersuch. ueber die Syphilis der 

 Affen," Akad. d. Wissensch. in Wien, 14, 1905. 



