( 624 ) 



still conhiiiis a (iiiaiititj of oatalase whereas ox-l>lood under the 

 same conditions no longer contains any catalase after half an hour. 

 Want of time prevented the above mentioned gentleman from pene- 

 trating any further in this matter, so that he left the treatment of 

 this subject to me. 



The loss of activity of the catalase of the blood by heating has 

 been investigated for ox-blood by Senter (/. c. p. 293). Those 

 investigations show that a diluted bloodsolution loses its activity in 

 a quarter of an hour at 65°, that the rapidity of decomposition is 

 considerably smaller at 55° and that the solution after having been 

 heated for three hours at 45° still contains 60 7o of the catalystic 

 power, .which it possessed originally. 



Moreover it appeared that the loss of activity is not proportional 

 to the present quantity of the enzyme, but that this phenomenon 

 takes place with constant rapidity. I thought it useful to investigate 

 the observed phenomenon with regard to some species of blood ') 

 more closely and to see at the same time if it was possible to 

 render the catalasereaction serviceable to the distinguishing of different 

 species of blood. 



Method of investigation. 5 cM* of the diiferent species of blood in 

 a dilution of 1 — 1000 are heated for half an hour at 63', then 

 cooled down to 15° and mixed with 3 cM'. of a hydrogenperoxide 

 solution of 17o- The mixture is put into a fermentation tube, such 

 as are used at the investigation of urine on glucose. If the mixture 

 still contains catalase the developing of oxygen begins within a few 

 minutes so that by the development of this gas it is indicated whether 

 catalase of the blood is present or not. 



Human- and monkey-blood (Macacus cynomolgus) investigated in 

 this way appeared to contain still catalase after having been heated 

 at 63° for half an hour, whereas the blood of horses, oxen, pigs, 

 goats, sheep, rabbits, cavies, rats, hares, chickens, pigeons, fish (flounder) 

 and frogs did not show any reaction after the described treatment 

 with H,0, and did not split off oxygen within 3 hours. 



Now the blood of some of these animals contains only a small 

 quantity of catalase, but in the liver this substance is present in 

 greater quantity. According to Battelli and Stern {Compt. rendus 

 138 [1904], 923-924) 10 mG. blood of a frog produces after being 

 mixed with H,0, of l"/», 7.5 cM.' oxygen in 5 minutes, whereas 



1) For the providing of species of blood I am indebted to Messrs. W. C. Schimmel 

 and M. G. de Bruin, of the veterinary school at Utrecht and to Dr. J. Büttikofer, 

 director of the zoological gardens at Rotterdam. 



