THE H^MOLYTIC PROPERTIES OF ORGAN EXTRACTS. 269 



If the organ extracts are heated to 56 C. for half or one hour 

 the hsemolytic property disappears in many cases; in other cases it 

 is diminished; very rarely it remains unchanged. According to 

 Tarassevitsch, this variation from the "cytases" (which in general 

 are destroyed by heating for half an hour to 56 C.) is only an apparent 

 one. In the organ extracts the " macrocy tase " is not completely 

 liberated, but is held back to a great extent by the cell detritus pres- 

 ent in the emulsion. It leaves the detritus only very slowly and 

 incompletely, as is shown by the fact that the entire emulsion is always 

 more active than the fluid portion obtained by centrifuging, and 

 also that by filtering through paper the clear fluid is deprived of the 

 greater part of the properties which the entire emulsion possesses. 

 This filtered fluid, in which, according to Tarassevitsch, all the 

 "cytases" present are in dissolved form, is said to behave toward 

 thermal influences like haemolytic serum. 



Finally according to Tarassevitsch the thermostability of the entire 

 extracts is not very great. If he heated his extracts a little higher, one 

 to two hours, to 58.5, 60, 62, the hcemolytic property disappeared com- 

 pletely. 



From this behavior toward thermic influences Tarassevitsch 

 concludes that the relationship of the haemolytic substances of the 

 organ extracts to the "cytases" of serum is perfectly clear, and that 

 it is incorrect to ascribe a haemolytic property which can be de- 

 stroyed at such low temperatures, to osmotic phenomena or to the 

 presence of "de quelques substances chimiques." Hence, as Metchni- 

 koff assumed, the organs in question contain a macrocy tase, and this 

 circumstance proves that the macrophagic organs must play a role in 

 the formation of the natural and the artificial haBmolysins. 



In the following pages we shall describe certain experiments in 

 which we have reached essentially different results from those obtained 

 by Metchnikoff and Tarassevitsch. 



The emulsion of the organs was prepared as follows: The organs removed 

 from the exsanguinated animals are rubbed up very finely with sea-sand which 

 has first been purified with hydrochloric acid. Then 5 to 10 times their weight 

 of physiological salt solution is added and the mixture thoroughly shaken 

 in a shaking-machine for two hours, whereupon the coarser particles are re- 

 moved through several hours' centrifuging. A more or less uniformly clouded 

 fluid remains. The organ extracts were employed as fresh as possible, though 

 it was found that they could well be preserved by freezing them at 10 to 

 -15C. 1 



1 On thawing them out we often observed the appearance of numerous 



