( 625 ) 



an equal quantity of tlie liver liberates 295 cM.' oxygen in the 

 same time. 



The liver of a frog was mixed with puritied sand, and the mixture 

 thus obtained was shaken with water. A drop of the decanted 

 liquid called about in a H,0,-solution a turbulent development of 0. 

 If 5 cM.' of the liquid was heated for half an hour it lost the power 

 of decomposing H,0, quite, so that also with a considerable original 

 catalytic power the above mentioned time is sufficient to make that 

 power disappear. 



In order to get an insight into the rapidity with which the catalase 

 of the blood loses its activity I put into practice the following method 

 of investigation for some species of blood. 



5 cM.' of the bloodsolution (1 — 1000) were put in some test-tubes; 

 the tubes and their contents were heated for some time varying 

 from — IJO minutes in the tliermostate at 63^ then cooled down 

 to 15° and mixed with 10 or 20 cM.' of a H,0,-solution of 1%. 

 The action having taken place, for 1'/, hour at 15^^, the catalase- 

 action was interrupted by adding 10 cM.' diluted sulphuric acid 

 and the quantity of hydrogenperoxide, which had not been decom- 

 posed was immediately titrated back with Vio N. Kaliumpermanganatic 

 solution. While the not heated bloodsolution indicates the quantity 

 of H,0, which is decomposed by 5 milligrams of the used blood- 

 species, it could be investigated at an arbitrary point of time in how 

 far the catalytic action had been weakened by the heating. 



At the used degree of concentration an oxidation of the catalytic 

 may originate by the H^Oj (Senter I.e. 279) but I would not reject 

 the advantages which are offered by larger concentration as it was 

 not wanted to get in the first place absolute figures. 



In the table mentioned below the results of my investigations are 

 written down while the graphic representation gives a more ample 

 survey . 



It is peculiar that here as well as at the blood investigations of 

 Uhlenhuth and those of Neisser and Sachs {Berl. klin. Wochenschr. 

 1905 N°. 44) the bloodspecies of related animals (man and monkey) 

 show a relation with regard to catalytic power concerning the 

 absolute strength as well as the greater resistance against the increase 

 of temperature. 



I think I may deduce from these investigations that the catalases 

 occurring in the blood of difterent species of animals are not identical. 

 My own observations, it is true extend to some individuals of the 

 different species of animals only, but from reports of Batelli and 



