Facts bearing on acquired immunity 247 



the pleura, as in guinea-pigs that are inoculated intra-peritoneally ? 

 Instead of being satisfied with merely examining the fluid exudation, 

 the surface of the pleura should have been scraped in order to ascertain 

 whether the phagocytic reaction was localised in this region. 



In any case such incomplete results on the active immunity of 

 rabbits in no way weaken the positive results obtained in the sub- 

 cutaneous tissue of the horse, in which the phagocytic reaction plays 

 a really preponderant part. 



This example of the streptococci completes our series of bacteria 

 in which we have studied their relations with the properties of the 

 animal organism that has acquired immunity. We have still to see 

 whether the acquired immunity against micro-organisms of animal 

 origin is subject to the same law as that against bacteria. 



For some years past a zealous study of the infectious diseases pro- 

 duced by animal micro-organisms has been carried out. Besides [260] 

 malaria, which occupies a most important position, attention has been 

 directed to certain diseases in domestic animals that are set up by 

 endoglobular haematozoa and by flagellata, and a fairly large number 

 of accurate data have been collected with regard to Texas fever and 

 its parasite the Piroplasma bigemhmm, as well as upon the epi- 

 zootic diseases due to Trypanosomata (Tsetse fly disease or Nagana, 

 "Dourine," etc.). 



We are indebted to Smith and Kilborne 1 for the earliest informa- 

 tion concerning the acquired immunity of Bovidae against Texas fever. 

 R Koch 2 then added some very precise observations on the immu- 

 nity of calves which had been inoculated with parasites attenuated in 

 the body of the tick (Boopliilus bovis). Lignieres 3 , who devoted 

 much attention to this question in the Argentine Republic, has dis- 

 covered a sure method of vaccinating the Bovidae against the 

 "Tristeza," the local name for Texas fever. He brought to Alfort 

 specimens of attenuated haematozoa, and in Nocard's presence 

 performed successful vaccination experiments. Lignieres is now 

 engaged in devising a practical method of ensuring immunity under 

 the special conditions found in the home of the "Tristeza." Up to the 

 present, however, there are no sufficient data as to the mechanism of 



1 Bulletin No. 1, Bureau of Animal Industry, U.S. Dep. of Agric., Washington, 

 1893. 



* " Reisebericht iiber Rinderpest etc.," Berlin, 1898. 



3 Rec. de med. vet., Paris, juillet, 1900, and Ann. de Vlnst. Pasteur, Paris, 1901, 

 t. xv, p. 121. 



