March 31, 1905.] 



SCIENCE. 



491 



this in the ordinary way, two per cent, of 

 Witte's peptone being added. It is dis- 

 pensed into Fernbach flasks, one liter in 

 each, and sterilized in the autoclave. Little 

 attention need be paid to the temperature, 

 it may vary anywhere from 115° to 120°, 

 0.2 per cent, of dextrose is added after 

 sterilization. The cultures are incubated 

 six days at 35°-36° C. The reaction of 

 the bouillon before sterilization is made 

 -|-.45, so that after sterilization it may be 

 -j-.75. Toxin made by this method has 

 been very uniform, rarely being below .005 

 c.c. for a 250-gram guinea-pig. 



(To be published in the Journal of Med- 

 ical Research.) 



On the Antagonism of Bacteria and their 

 Products towards Other Bacteria: L. F. 

 Eettger, Sheffield Scientific School, Yale 

 University. 



Considerable attention has been given in 

 recent years to the influence that one micro- 

 organism is capable of exerting on the life 

 and growth of another. We learn, on the 

 one hand, that certain bacteria profit by 

 association. Again, there are numerous 

 instances in which the presence of one or- 

 ganism, or its products, is inimical to the 

 development of another. For example, the 

 pyocyaneus bacillus has been found to act 

 in a very antagonistic manner toward the 

 anthrax bacillus. And not only is this 

 true of the living bacilli themselves, but 

 also of certain of their products. Emmer- 

 ich and Loew claim to have succeeded in 

 immunizing rabbits against anthrax by the 

 use of their so-called 'pyocyanase, ' which 

 they prepared from old bouillon cultures 

 of B. pyocyaneus. 



In a study of the chemical and physiolog- 

 ical properties of B. prodigiosus and its 

 products, I observed, among other things, 

 that sterile cultures or preparations of the 

 prodigiosus bacillus exerted a strong pro- 

 tective action against experimental anthrax 

 when injected in small quantities under the 



skin or into the peritoneal cavity of guinea- 

 pigs. Of nine experiments that were car- 

 ried out in full, seven yielded very positive 

 results. In the eighth the animal died as 

 a result of over-dosing with the prodigiosus 

 material ; and in the ninth, both the pro- 

 digiosus and control animal lived, owing 

 to the small number of anthrax bacilli in- 

 jected (47). In six of the seven experi- 

 ments that gave positive results, the life of 

 the guinea-pig was prolonged 14, 24, 25, 

 26 and 72 hours, respectively ; while in the 

 seventh the animal entirely recovered. 



The prodigiosus material used for injec- 

 tion was prepared from potato cultures of 

 the prodigiosus bacillus. The cultures 

 were scraped and allowed to stand under 

 chloroform for twenty- four hours. After 

 drying in an exhaust desiccator, the mass 

 was ground into a fine powder. Definite 

 quantities of this 'prodigiosus powder' 

 (0.05 to 0.1 gram) were mixed with ten 

 cubic centimeters of sterile physiological 

 salt solution, and after filtration through 

 loose absorbent cotton definite amounts of 

 the suspension were injected, usually under 

 the skin of the abdomen and in rather close 

 proximity to the site of the anthrax injec- 

 tion. 



For inoculation with anthrax, young 

 agar cultures were employed. The bacilli 

 were suspended in physiological salt solu- 

 tion, and their number was approximately 

 determined by the use of agar plates. The 

 inoculation with anthrax was made under 

 the skin of the abdomen. In all the ex- 

 periments control animals were employed. 



Although sterile prodigiosus powder ex- 

 erts such a pronounced protective action 

 against anthrax, there remains at present 

 one serious objection to its employment in 

 practical immunization work. It exerts 

 such a degree of toxic action, when injected, 

 that only very small quantities can be used 

 without serious consequence to the animals. 

 Attempts thus far made to destroy the tnxic 



