PARASITIC AND PATHOGENIC BACTERIA 99 



conjunctival sac, which receives the washings from the conjunctiva, 

 is probably the recipient of many bacteria; of these B. xerosis occurs 

 with sufficient regularity in the conjunctival sac to be regarded as a 

 normal inhabitant. The pneumococcus is also found there. These 

 organisms are "opportunists," occasionally causing severe acute 

 conjunctivitis, although usually they are benign. Certain bacteria 

 affect the conjunctiva fairly readily. Among these organisms, the 

 gonococcus is particularly troublesome, causing a most severe inflam- 

 mation. Ophthalmia neonatorum, a gonorrheal infection of the con- 

 junctivse of the newborn of infected mothers, has been in the past 

 a most common cause of blindness. It has been claimed that the 

 meningococcus may occasionally pass from the eye through the tear 

 duct to the nasal cavity, and from there to the meninges. 



Subcutaneous Tissue.- Many bacteria, particularly exogenous 

 pathogenic bacteria, do not develop in the subcutaneous tissues, as 

 for example, the majority of those organisms which induce specific pro- 

 gressive disease from man to man such as typhoid and cholera organ- 

 isms. On the other hand, many of those bacteria which are habitually 

 parasitic on the skin may produce infections of the subcutaneous 

 tissues which vary in severity from mild inflammations to severe 

 cellulitis. The staphylococci and streptococci are among the more 

 important of this type. 



Tonsils. The crypts of the tonsils afford mechanical protection 

 to bacteria which gain access to them and the secretions and tissue 

 undoubtedly provide the necessary nutritive elements, consequently 

 it is not surprising to find many types of bacteria in them. Staphy- 

 lococci are almost invariably present and streptococci, particularly 

 non-hemolytic varieties, are very common. The tonsils, which are 

 in very direct communication with the lymphatic system, are impor- 

 tant atria of invasion, particularly for streptococci, and many cases 

 of low-grade infections of the body appear to have originated from 

 the passage of bacteria through the tonsils to the tissues of the body. 

 The extent to which the normal tonsils destroy bacteria their value 

 in the non-specific initial defense of the body against bacterial invasion 

 in other words is not clearly established. Generally speaking, how- 

 ever, the tonsils appear to bear the brunt of attack in certain diseases 

 and they are of undoubted importance in shielding the body from 

 invasion through the lymphatic tract by directly holding back these 

 bacteria. The promiscuous removal of tonsils, particularly in the 

 young, has no justification from available knowledge. The removal 

 of diseased tonsils is quite a different matter. 



