DIPHTHERIA BACILLUS. 



399 



fully described by Loeffler in 1884. It answers all 

 Koch's laws in its relationship to the disease of 

 diphtheria. It is a non-motile, rod-shaped organ- character- 

 ism having about the length of the tubercle bacil- 

 lus, but twice its thickness. One end commonly 

 presents a flask-like enlargement. It stains by 

 Gram's method, with the ordinary anilin dyes, and 

 with the special stain of Neisser shows a peculiar 

 granulation, the granules of Babes-Ernst. It is 

 readily cultivated, especially on solid media which 

 contain serum and in various bouillons. It tends 

 to grow in coherent masses and under the micro- 

 scope the cells often show a characteristic phalanx- 

 like arrangement. 



The diphtheria bacillus is an obligate parasite 

 having no vegetative existence outside of the body, 

 is very resistant to desiccation and may remain 

 virulent in a dried state for from one to five 

 months. Its life in water varies from a few days 

 to several weeks, having its shortest existence in 

 distilled water and its longest in hydrant water 

 which has been boiled. It disappears more quickly 

 from unboiled hydrant water. It is very suscepti- 

 ble to ordinary antiseptics, being killed in a few 

 minutes by corrosive sublimate even in a dilution 

 of 1 to 10,000. 



The sources of infection may be enumerated as 

 follows: 1. From the false membranes, sputum 

 or excretions of the mouth, pharynx, nose, con- 

 junctiva and deeper respiratory passages of in- 

 fected individuals. 2. From convalescents and 

 those who have fully recovered, even after serum 

 treatment. Virulent organisms may persist in the 

 pharynx or nose of convalescents for weeks and 

 months, as in one of Prip's cases in which they 



Methods of 

 Infection. 



