508 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tissues is straighl or slightly curved. In cultures the organisms are very 

 polymorphic, sinuous and filamentous forms occurring. The bacilli are 

 generally isolated, but sometimes they form short chains. The ex- 

 tremities are blunt. The bacillus is readily stained by aniline dyes, but 

 retains the stain in Gram's method with some difficulty. The motility 

 which it exhibits in pathological exudates is lost in growth in liquid 

 media. The organism forms spores; the spores are oblong or egg- 

 shaped, almost always terminal or sub-terminal, more rarely central. 

 After twenty-four hours on Veillon's agar the colonies appear as small 

 points, visible to the naked eye. When magnified they appear to possess 

 a brownish-yellow central mass surrounded by a clear halo of irregular 

 outline. The cultures in glucose broth have a putrid odour. Spores are 

 formed in ordinary broth, less so in lactic broth, and not at all in glucose 

 broth. Milk, to which calcium carbonate has been added, is coagulated 

 in two or three days, the casein clot undergoing progressive digestion. 

 The organism is very virulent for the guiuea-pig. 



Biological Researches on the Eosinophils.* — M. Weinberg and 

 P. Seguin have conducted an important research on the biological 

 properties of the eosinophile leucocytes. They have shown that these 

 cells possess phagocytic properties, being capable of ingesting inert 

 matter (animal black), and of phagocyting many species of bacteria and 

 protozoa, and also red blood corpuscles. The organisms used in their 

 experiments included staphylococci, sarcime, streptococci, gonococci, 

 meningococci, Bacillus anthracis, B. Coli, B. diphtherise, B. tetragenus i 

 Monilia allicans, Sporotrichum Beurmanni, Spirochseta gallinarum, Hetero- 

 mita cavise, and Trypanosoma Evansi. The experiments were conducted 

 either in vitro, using guinea-pig leucocytes, or in vivo (peritoneal cavity 

 of the guinea-pig, subcutaneous tissues, circulating blood, etc.). From 

 experiments conducted with B. subtilis, B. coli, protozoa and red cells, 

 it "was concluded that the eosinophils were not only able to engulf but 

 could also digest these elements. When the eosinophiles are very 

 abundant in the blood, or when they accumulate at the seat of inocula- 

 tion, they play an important role in the immediate protection of the 

 organism against infection. 



Although the eosinophiles possess the various properties above 

 enumerated, they only play a subsidiary role in phagocytosis, their 

 principal function being the absorption of toxic products. When eosino- 

 phile leucocytes were placed in contact with the fluid from a hydatid 

 cyst for a period of one hour, it was found that they no longer exhibited 

 their phagocytic properties, although the other leucocytes present 

 (neutrophils and mononuclears) remained capable of ingesting bacteria. 

 The eosinophiles possess the power of absorbing hydatid fluid, the fluid 

 in question losing its antigenic properties when placed in contact with 

 an appropriate number of eosinophiles. This fact is easily demonstrated 

 by use of the complement-fixation reaction with a fresh echinococcus 

 serum, normal hydatid fluid being used as a control. The eosinophiles 

 of immunized animals absorb the hydatid antigen more easily than the 

 eosinophiles of normal animals. 



* Ann. Inst. Pasteur, xxix. (1915) pp. 323-45 (2 pis.). 



