1899] MICROSCOPICAL JOURNAL. 221 



two remaining - cows which were classed as doubtful were 

 both found to be tuberculous. In the formation of the new 

 dairy herd at Windsor, all animals purchased for it will be 

 tested, and admitted only when they do not react. 



UEDICAL MICROSCOPY. 



Plague Serum as a Therapeutic Agent. — W. Symmers, 

 of Cairo, gives a record of experiments made to determine 

 the therapeutic efficacy of plague serum ("Centralb. f. 

 Bakt."), carried out at the Serum Institute at Abbasieh, in 

 Egypt. Cultures were made from the bacilli of bubonic 

 plague obtained from Bombay, and experiments tried on 

 guinea-pigs, white rats and mice, and horses. Cultures on 

 agar or on bouillon were found to possess little virulence, 

 and it was necessary to pass the bacilli through white mice 

 before sufficient virulence could be obtained. Cultures 

 from these were then made in neutral bouillon or agar 

 agar, and measured quantities injected into horses, gener- 

 ally into the subcutaneous tissues of the neck. Local 

 swelling and inflammation extending to the glands, and 

 slight (febrile) rise of temperture followed, but in no case 

 was there much constitutional disturbance. After repeat- 

 ed injections of sterilized bouillon or agar cultures at a 

 temperature of 60 deg. C, or of the living bacilli — some- 

 times as many as fifteen injections being given — the jugu- 

 lar vein was opened, and the blood thus withdrawn was 

 centrifugalized and serum obtained. The minimum fatal 

 dose of live cultures being separately determined, quanti- 

 ties of serum were now mixed with these, and the mixture 

 was injected into the peritoneal cavity of white rats. It 

 was found that serum from the horse treated with live cul- 

 tures gave but feeble antitoxic power, while the horse 

 treated with sterilized agar cultures furnishes the strong- 

 est serum, and of this a quantity equal to % c.cm. was suf- 

 ficient to preserve white rats against the minimum fatal 

 dose of the bacillus ; smaller quantities of the serum 

 proved insufficient. From all the experiments made it 

 was concluded that the antitoxic power of the serum was 



