Pathogenesis 499 



red-brown. The blood with which the cavities of the heart 

 are filled is firmly coagulated, and, like that in other organs 

 of the body, contains large numbers of the bacteria, most of 

 which exhibit a lanceolate form and have distinct capsules. 

 The disease is thus shown to be a bacteremia unassociated 

 with conspicuous tissue changes. 



In such cases the lungs show no consolidation. Even if 

 the inoculation be made by a hypodermic needle plunged 

 through the breast-wall into the pulmonary tissue, pneu- 

 monia rarely results. Gamaleia* reported that pneumonic 

 consolidation of the lungs of dogs and sheep could be brought 

 about by injecting the pneumococcus through the chest- 

 wall into the lung. Tchistowitsch f stated that by intra- 

 tracheal injections of cultures into dogs he succeeded in 

 producing in 7 out of 19 experiments typical pneumonic 

 lesions. Monti { claimed to have found that a characteristic 

 croupous pneumonia results from the injection of cultures 

 into the trachea of susceptible animals. A very interesting 

 review of the literature of the experimental aspects of the 

 subject, embracing 198 references, will be found in Wads- 

 worth's paper upon " Experimental Studies on the Etiology 

 of Acute Pneumonitis." 



The final proof that true pulmonary consolidation, i. e., 

 pneumonia, can be produced experimentally by cultures of 

 the pneumococcus is to be found in a paper by Lamar and 

 Meltzer.|| These investigators etherized dogs, kept the 

 mouth open by means of a large wooden gag, drew the tongue 

 forward by means of hemostatic forceps, and then, seizing the 

 median glosso-epiglottic fold, pulled it forward so that the 

 posterior aspect of the epiglottis presented an inclined 

 plane. Into this concavity one end of a tube is placed. 

 Under the protection of the left index-finger the tube was 

 directed into the larynx and pushed down slowly and gently 

 through the trachea until a resistance was met with. The 

 inner end of the tube was then found to engage in a bronchus 

 usually the right bronchus. A pipet containing a liquid 

 culture of the pneumococcus was next attached to the 

 external end of the tube, and by means of a syringe the 



* "Ann. de 1'Inst. Pasteur," 1888, u, 440. 



t Ibid., 1890, m, 285. 



J "Zeitschrift fur Hygiene," etc., 1892, xi, 387. 



\ "Amer. Med. Jour. Sciences," 1904, cxxvn, p. 851. 



|| "Jour. Exp. Med.," 1912, xv, No. 2, p. 133. 



