CLASSIFICATION. 119 



katalases, in contradistinction to the oxydases, do not blue tincture 

 of guaiac either directly or in the presence of hydrogen peroxide. 



The oxydases occur widely distributed in the animal and especi- 

 ally in the vegetable world ; they include the laccase, which causes 

 the formation of the black Japanese lacquer ; various tyrosinases, one 

 of which causes the transformation of tyrosin to homogentisinic acid, 

 while another is responsible for the transformation of the black pig- 

 ment secreted by the octopus ; an indophenol oxydase, which forms 

 indophenol from paraphenylendiamin and a-naphthol ; aldehydases 

 which oxidize aldehydes to the corresponding acids, etc. 



To this group probably also belong the glucolytic ferments, which 

 have been demonstrated in many organs of the animal body, notably 

 the muscle-tissue and the liver; in both instances they are apparently 

 activated by a kinase furnished by the pancreas. 



12. The Coagulating Ferments. These include the fibrin ferment 

 which causes the coagulation of blood ; various milk-curdling fer- 

 ments which occur both in the animal and the vegetable world ; a 

 ferment which is thought to be responsible for the coagulation of 

 myosin ; pectase, which coagulates the pectins of plants and leads to 

 the formation of pectic acid, etc. 



13. Reducing Ferments (Reductases). Such ferments apparently 

 also exist. One has been described which reduces sulphur to hydro- 

 gen sulphide. 



14. The Kinases. These are ferment-like substances which mani- 

 fest their peculiar activity by the activation of other ferments, viz., 

 their zymogens. Enterokinase thus activates the trypsinogen of the 

 pancreas. Another kinase furnished by the pancreas activates the 

 glucolytic substances found in liver and muscle tissue, etc. 



