§ XIII.] Malaria. Typhoid fever. 171 



Cuboni and Marchiafava have obtained in animals, into which 

 they had injected the blood of persons suffering from inter- 

 mittent fever, symptoms which they considered to be those of 

 malaria-infection. I am not in a position to say how far these 

 symptoms observed in animals after infection may, or ought to 

 be regarded as sure signs of the presence of malarial fever. 



On the other hand it is obvious that the injection of some 

 cubic centimetres of fluid containing particles of soil or of a 

 Bacillus-culture does not really correspond to an ordinary in- 

 fection, in which a very minute portion of the contagium is in 

 every case absorbed, introduced by inoculation or inhaled. 

 And with respect to the descriptions given in the different pub- 

 lications of the Bacteria which were examined, we cannot be 

 sure whether one species of Bacterium was present in each case 

 or more than one, or whether the forms which one observer saw 

 in the blood were the same or of the same species as those 

 which others grew from soil-specimens. It therefore does not 

 seem to me that we have before us any precise determination of 

 the nature of the contagium or miasma vivum of malaria, but 

 that the question has now to be really attacked on the basis of 

 the former laborious investigations and with careful sifting of 

 their results. That these remarks, which appeared in the first 

 German edition of this book, were not without good foundation 

 is shown by the latest reports, especially those of Marchiafava 

 and Celli, in which it is stated that the contagium of malaria 

 is not a Bacterium, but a small amoeboid • organism which 

 penetrates into the red blood-corpuscles. We must hope for 

 clear and decisive investigations into this organism. 



ro. Our knowledge concerning the causal connection between 

 Bacteria or parasites generally, and typhoid fever and diphtheria 

 in men is also at present uncertain, notwithstanding Gaffky's 

 and Loffler's model investigations. 



Typhoid fever is a distinctly miasmatic infectious disease, 

 which may sometimes become contagious. Causal relations 

 between its appearance and certain localities and the use of 



