196 



Scientific Proceedings (108). 



lung by way of the peribronchial and periarteriolar structures 

 into the pulmonary tissue. Infection of the lung occurs under 

 these conditions even though cultures from the lower trachea are 

 sterile. 



An abundant lymphatic system can be demonstrated by the 

 injection of India ink into the submucosa of the trachea. This 

 plexus extends from the epiglottis downward as far as the bifur- 

 cation of the trachea and connects directly with similar plexi in 

 the submucosa of each bronchus. With further subdivisions of 

 the bronchi, the condition noted above is duplicated. At the 

 points of bifurcation throughout the cartilage-bearing bronchi, 

 anastomotic branches connect the plexi with the periarteriolar 

 lymphatics, and other branches pass directly to the regional lymph 

 glands. Thus a short circuit around the valves of the deeper 

 pulmonary lymphatics is provided. 



The distribution and extension of these tracheal lymphatics 

 can be demonstrated equally well by Gram-stained sections pre- 

 pared from an animal inoculated through the submucosa of the 

 trachea by injection or insufflation of virulent pneumococci. 

 The presence of the organisms shows the distribution of the infec- 

 tion through the lymphatics of the submucosa of the trachea, 

 past the hilum of the lung, into the pulmonary parenchyma. 

 Thus a direct pathway of infection is provided. On the other 

 hand, the manner in which the lymphatic plexi are sharply demar- 

 cated at the bifurcations of the trachea and bronchi suggests 

 that this lymphatic system may also serve as a protective mech- 

 anism, since, undoubtedly, many of the invading bacteria are, 

 at these points, diverted to the protective regional lymph glands. 



104 (1564) 



The life of the white mouse. 



By W. B. Kirkham (by invitation). 



[From the Osborn Zoological Laboratory of Yale University, New 



Haven, Conn.] 



White mice may give birth to young every month in the year, 

 but most of the litters come during the warmer months. Males 



