160 TOXINES AND ANTITOXINES. 



they succeeded in eliminating their toxic power almost com- 

 pletely without destroying the immunising capacity. The serum 

 of the animals used in the experiments contained a specific 

 antitoxine which neutralised the dissolved poison in vitro and 

 after previous injection. At the same time, both the toxic 

 capacity and formation of antitoxine were very limited in 

 extent. 



Almost identical results were obtained about the same time 

 by FOA and CARBONE ] and ScABiA, 2 who also succeeded in 

 producing antitoxic immunity by means of germ-free filtrates 

 and glycerin extracts of blood from animals infected with 

 pneumonia. 



BELFANTi, 3 too, produced immunity, though only to a very 

 slight extent, by means of filtered germ-free sputum. 



FOA also succeeded in separating the immunising principle by 

 precipitation with alcohol or ammonium sulphate. 



PANE 4 found filtered cultivations to be very slightly poisonous. 

 WASHBOURNE 5 states that he, too, was able to produce immunity 

 with filtered cultures. 



IsAEFF 6 found that pneumococci produced only slightly toxic 

 products in the ordinary culture media, but that their toxic 

 power could be considerably increased by frequent, at least 

 twelve, passages through rabbits. From the blood of the heart 

 of such rabbits he obtained, by the addition of 1 per cent, of 

 glycerin and some sodium carbonate, followed by filtration 

 through a Chamberland filter, a poison which killed rabbits when 

 introduced in the proportion of 1 per cent, of their body weight, 

 and was greatly weakened when heated at 70 C., and destroyed 

 at 100 C. The fluid from the peritoneum of such animals was 

 very poisonous, but not fatal, after being sterilised by heat. 

 Although he, too, produced a certain degree of immunity by 

 means of germ-free filtrates, he yet asserted that he was abso- 

 lutely unable to observe any antitoxic immunity, and that it was 

 only antibacterial. 



1 Foa and Carbone, "Sulla immunita verso il diplococco pneumonico, " 

 Gazz. med. di Torino, 1891, 1 ( Centralbl. f. Bah., x., 768). 



2 Foa and Scabia, "Sulla immunita della pulmonite," ibid., 1892, 13-15 

 (Centralbl. f. Bakt., xi., 615). 



3 Belfanti, "Sulla immunisazione per mezzo di filtrati di sputo pneu- 

 monico," Rtf. Med., 1892, 126 (Centralbl. f. Bakt., xii., 401). 



4 Pane, " Ueber d. Heilkraft d. antipneumon. Serums," Centralbl. f. 

 Bah., xxi., 664, 1897. 



5 Washbourne, ' ' Experiments with the Pneumococcus, " Journ. of Path. , 

 iii., 142; Baumgartens Jb., 1895, 62. 



6 Isaeff, " L'immunit^ centre le pneumocoque,'Mnn. Past., vii., 259, 1893. 



