548 NEISSERIA 



Pathogenicity. — The gonococcus is not only a strict parasite, but it is a specific- 

 ally human parasite. Of the numerous attempts which have been made to 

 reproduce gonorrhoea in animals other than man, not one has been successful 

 (Leistikow 1882, Neisser 1882, Bumm 1885a, Nicolaysen 1897). Neither inoculation 

 of pus nor of pure cultures on to the mucosa of the urethra or conjunctiva gives rise 

 to disease, even in the anthropoid apes. Experiments on the lower animals, how- 

 ever, have shown that the injection of gonococci directly into the peritoneum or the 

 blood stream frequently proves fatal, and that severe local inflammation may be 

 set up by injecting the organisms into the anterior chamber of the eye or into a 

 joint cavity. 



Mice. — Subcutaneous injection of pure cultures is without eflfect. Intraperitoneal 

 injection of a saline suspension of a young serum agar culture is often fatal in 24 hours. 

 Post mortem, there is slight congestion of the peritoneum, and sometimes a small amount 

 of viscous exudate, containing pus ceUs. Gonococci are found in varying numbers, both 

 intra- and extra- cellular in position. They may frequently be cultivated from the peri- 

 toneum, and occasionally from the heart's blood. With smaller doses, many of the mice 

 do not succumb for 2 to 3 days ; at necropsy in these mice it is rare to find gonococci 

 microscopically, and cultures are uniformly sterile. Some mice siu-vive without showing 

 signs of illness. Almost exactly the same results foUow the injection of cultures which 

 have been killed by heatmg to 70° C. for 1 hour (Wassermann 1898). There is no increase 

 of virulence by passage. 



GtriNEA-PiGS. — Intraperitoneal injection of 5 ml. of a 6-days' serum broth culture 

 (Nicolaysen 1897), or of a 24-hours' growth on a Blake bottle of serum glucose agar (WoU- 

 stein 1907), kiUs the animals in 24 hours as a rule. Post mortem, there is congestion of the 

 serosa, with small haemorrhages ; a fittle clear or turbid fluid in the peritoneal cavity ; 

 oedema of the pancreas and surrounding tissues ; congestion or haemorrhage into the 

 adrenals ; a layer of fibrin and pus over the Uver, spleen and omentum ; sometimes clear 

 fluid in the pleural cavities. Films from the peritoneum and omentum show varying 

 numbers of polymorphonuclears, and diplococci situated intra- and extra-ceUularly. 

 Cultures from the peritoneum are generally positive. It will be seen that the post-mortem 

 findings are similar to those following injection of guinea-pigs with meningococci ; as a 

 rule, however, larger doses of gonococci are required to produce the same effect. After 

 some generations in vitro the gonococci lose their virulence, and become innocuous to 

 guinea-pigs. 



Rabbits. — Subcutaneous injection of 10 ml. of a 4 to 5-days' serum broth culture 

 (Maslovski 1900) gives rise to shght inflammatory sweUing after 24 hours ; later suppuration 

 occurs, so that in 10 days a small abscess is formed, containing thick, sterile pus. The 

 temperature rises somewhat, and the animal loses weight. The same result foUows the 

 injection of heat-killed cultures. Smaller doses are without effect. 



Intraperitoneal injection of large doses of gonococci, washed off yoimg serum agar 

 cultures, kills the animal in 24 hours. Post mortem, there is some peritoneal reaction, 

 and the organisms may be cultivated from the peritoneum, and occasionally from the 

 heart's blood. Bruckner and Cristeanu (1906c) claimed to have raised the virulence to 

 such an extent that a rabbit injected intraperitoneaUy with 1/20 of a serum agar slant 

 died in 2-10 hours. These results have not been confirmed. 



Intravenous injection produces fatal results with smaller doses. The gonococci may be 

 recovered from the blood after 24, sometimes after 48 hours. The results of different 

 workers are, however, at variance. Vannod (1907), for example, injected hving cocci 

 in a dose of 5 ml. of an ascitic peptone broth culture intravenously into rabbits, and obtained 

 practically no reaction. 



Maslovski (1900) injected a few drops of a 3-day's serum broth culture into the anterior 

 chamber of the eye of rabbits. The following day there was diffuse turbidity of the cornea, 



