VII] CHEMISTRY OF BACTERIA 131 



as also in the body affected with the disease, specific 

 toxins. 



10. Many species of bacteria include in their proto- 

 plasmic bodies substances which when injected in sufficient 

 doses into the subcutaneous tissue — or, better still, into the 

 peritoneal cavity — of rodents, produce symptoms of disease 

 and death. Bacteria of various kinds, and not having any 

 connection with infectious disease — in fact, harmless and 

 non-pathogenic — can, when injected in sufficient doses into 

 the peritoneal cavity of guinea-pigs, set up acute intensive 

 peritonitis and death in 16 to 20 hours. If, for instance, 

 ■g- to J- of an Agar surface culture (6 cm. by 2 cm.) ^ of 

 bacillus prodigiosus, bacillus subtilis, bacillus coli, bacillus 

 proteus vulgaris, vibrio of Finkler — all microbes which have 

 no connection with any infectious disease of man or 

 animals — be injected into the peritoneal cavity of a healthy 

 guinea-pig, the animal shows decided illness already after a 

 few hours : first rise, then decided fall, of temperature ; 

 it is quiet, refuses food ; later on, its movements become 

 impaired, and it may be found dead in 18 to 24 hours. 

 The rapidity with which death takes place depends on the 

 size of the animal and on the quantity injected. After death 

 extensive and intensive peritonitis is found : solid lymph on 

 the peritpneum, pseudo-membranes on the liver, spleen, and 

 omentum ; the intestine is as a rule greatly congested, and 

 there is more or less copious peritoneal exudation, either 

 turbid or sanguineous. If the culture has been injected as 

 living culture, the peritoneal exudation is crowded with 



' The culture is made by rubbing over tiie whole slanting surface of 

 the agar a platinum loop dipped previously into the active culture, 

 then incubating at 37° C. for forty-eight hours. A definite quantity 

 of broth (sterile) is then added, and the growth rubbed down with the 

 platinum loop ; the turbid emulsion is poured off and used for injection, 



K 2 



