1883.] On the Infectivity of the Blood and other Fluids, 451 



involved has recently acquired fresh importance in reference to the 

 relations of the lower fungi to disease, and the occurrence in them, as 

 lately asserted by Dr. Hans Biichner,* P. Grawitz,f and others, of a 

 transmutation of physiological species under altered conditions. 



In observations recently made upon septichaemia in the mouse, % 

 and other experiments, I obtained results which seemed to me to 

 negative the occurrence of any progressive increase of virulence in 

 the blood in successive inoculations, or of any transformation, physio- 

 logical or morphological, in the organisms present, an opinion which 

 was confirmed and the question discussed by Dr. R. Koch,§ in a 

 work recently published. 



In the case of the mouse, from the small size of the animal and the 

 blood in most cases being more or less coagulated when examined, it 

 was not easy to obtain accurately measured minute fractional quan- 

 tities, by successive dilutions, for the purposes of experiment ; for 

 which reason, and also as it was with reference chiefly to the blood of 

 the rabbit that the statements had originally been made, I selected 

 that animal for the investigation of this question by the following 

 methods. 



To originate infection in the same manner as in other experiments 

 on the same subject, putrid blood was used, generally that of the ox ; 

 but I have also employed that of the pig, sheep, &c, or of the rabbit 

 itself, all with similar results. Of such blood, diluted with an equal 

 bulk of normal saline solution and strained, a few drops were injected 

 into the subcutaneous tissue of the back or abdomen, by means of a 

 Pravaz syringe. In the subsequent high dilutions five or ten drops 

 were generally injected, and these comparatively large quantities were 

 employed in order that there might be less chance of error in the 

 quantity of blood actually received by the animal, than would be the 

 case with smaller injections, e.g., of one drop, as used by Davaine ; 

 though his method probably reduces the liability to formation of 

 abscesses at the site of injection, with the accompanying failure of 

 infection, which, however, only occurred to me in a few instances. In 

 these experiments, where it was requisite to guard against the possi- 

 bility of accidental infection or contamination, instead of a syringe I 

 used a glass tube drawn out to a fine point ; this is readily inserted 

 under the skin of the back in young animals, still more so under that 

 of the abdomen. When the quantity to be injected requires to be 

 accurately measured, it is easy once for all to calibrate the tubing by 

 the usual method, and extemporise a graduated pipette, containing a 

 given quantity, between two marks of the file. 



* " Sitzber. k. B. Akad. Wiss. zu Miinchen," 1880. 



f Virchow, " Archiv.," Bd. 81, H. 2, s. 355. 



% " Qrly. Joum. Micros. Sc.," N.S., No. 85, January, 1882, pp. 66-75. 



§ " Untersuch. u. d. iEtiol. d. Wundinfectionskrankheiten, &c," Leipzig, 1878. 



