460 PATHOGENIC MICROORGANISMS 



Winternitz, Smith and Robinson 67 have, however, recently sug- 

 gested another possibility. They have called attention to the fact 

 that there is a rich plexus of lymphatics about the trachea, within 

 the submucosa. They believe that the nature of the tracheal and 

 bronchial submucosa, with its ciliated mucous epithelium, renders 

 it extremely difficult for bacteria and other materials to reach the 

 lung by this open route under normal conditions, and call attention 

 to the great difficulty which has been encountered in attempts to 

 produce disease by mere inhalation without pulmonary irritation 

 or injury of the respiratory tract. Their idea is that infection of 

 the lung is accomplished by the entrance of the bacteria into the 

 lymphatics surrounding the trachea through some injury to the 

 nmcosa and are then afforded a direct path for infection. In experi- 

 mental work either the infecting needle or the catheter may produce 

 preliminary injury and lymphatic inoculation. They support their 

 contention by inoculating rabbits both by tracheal injection with 

 a needle, and by catheters, and finding in successful infections that 

 the lymphatics referred to were involved. 



According to Cole, 68 when pneumonia is secondary to septicemia 

 it is usually of the lobular type. Experiments of Meltzer seem to 

 indicate that infection is facilitated by closure of the small bron- 

 chioles, and cold or chilling may possibly stimulate the mucous 

 glands so as to plug these. 



In the course of the development of pneumonia the infecting 

 organisms are, of course, located in the pulmonary alveolae and the 

 smaller bronchioles, and appear in the sputum. Since the possibility 

 of specific serum therapy which will be dealt with in detail below 

 have made it desirable not only to determine whether the disease 

 is caused by the pneumococcus, but also have necessitated our 

 knowing which particular type is responsible in the individual case, 

 all pneumonia cases should be typed whenever possible. 



Typing from Sputum. A technique for this has been developed 

 by the workers mentioned above and the technique of Dochez and 

 Avery, with no essential changes, but a few additional remarks, 

 is as follows: Since it is important not to confuse the lung invader 

 with adventitious pneumococci present in the mouth, the collection 

 of the sputum is an important part of the technique. Failure to 



67 Winternits, Smith and Eobinson, Bull. Johns Hopkins Hosp., 31, 1920, 63. 



68 Cole, Harvey Lecture, New York, Dec. 13, 1913. 



