1897] MICROSCOPICAL JOURNAL. 163 



4. When grown upon 10 ])cr cent gelatin, colonies of the 

 xerosis bacillus are not visible to the naked eye within 

 forty-eight hours; the colonies of diphtheria bacilli can be 

 recog"nized in twelve to twenty-four hours. 



5. The invariably innocuous nature of the bouillon cul- 

 tures of the xerosis bacillus, when innoculated into the 

 subcutaneous tissues of animals is susceptible to the bacil- 

 lus of diphtheria. 



As to the exact nature of the xerosis bacillus — whether 

 it be a non-virulent and slig-htly altered species of the 

 bacillus diphtheria?, or a totally separate and distinct bacil- 

 lus — it is impossible at present to decide. 



Leucocytes and the Bactericidal Action of the Blood. — 

 Hahn (Arch. f. Hyg-., vol. xxv, p. 105) has investigated the 

 action of blood serum and also the pleural exudation of 

 rabbits. The leucocytes ni the latter are destroyed by 

 freezing. He found that the exudate had a more powerful 

 bactericidal action upon Staphylococcus pyogenes aureus 

 and bacillus typhosis than the blood serum or the defribi- 

 nated blood of the same animal; and since the leucocytes 

 were destroyed, the action cannot depend upon phagocyto- 

 sis in Metchnikoff's sense of the term. The author made 

 experiments with Lichenfeld's histin-blood, in which the 

 leucocytes remained unaffected, in order to determine 

 whether the bactericidal power depends upon the destruc- 

 tion of leucocytes or upon substances secreted by the 

 leucocytes while still alive. He came to the conclusion 

 that the latter is the more probable explanation. 



Bubonic Plague Bacillus. — Dr. Alvah H. Doty g-ives a 

 full account of the history and g-erm of the bubonic plag"ue. 

 Intheyear 542 Kgypt wasconsideredthehomeof theplag-ue. 

 Between 660 and 680 Eng-land was invaded. In 1334 it was 

 broug-ht from the East, where it was supposed to have had 

 its origin. Sicily 1346, Norway 1351. The mortality was 

 enormous. During- the eig^hteenth century the plag*ue 

 existed only in Eastern Europe, Asia and Africa. A slight 

 outbreak occurred in Delmatia in 1840, and a severe one on 

 the Volg-a, in the province of Astrakan in Russia, 1878 79. 



