84 



dant. Its small, delicious fruit is an important article of trade, 

 under the name of "Garambulla." 



As we approach the valley of Mexico, we come into a more 

 fertile region, producing tropical fruits and other products indi- 

 cating the rich luxuriance which we are to encounter after 

 another day's journey to the south or east. The mountain 

 flora of the vicinity of Mexico is of special interest and beauty. 

 Here there are many species of salvia, oxalis, verbena, geranium, 

 Solanum, etc. Terrestrial orchids are decidedly numerous, 

 though scarcely abundant, and the instant that we penetrate 

 to the warm and moist valleys, even quite near to the city, 

 interesting and handsome arboreal species begin to appear. 

 Arboreal ferns, tillandsias and other bromeliads are also nu- 

 merous. In rich places among the rocks dahlias of various 

 colors are common and abundant. 



(To be continued) 



THE NATURE AND FUNCTION OF THE PLANT 

 OXIDASES 



By Ernest D. Clark 

 {Coniinued front March Torreya) 



Function of the Oxidases in the Plant 



\^' Physiology 



It is evident from the preceding chapters that oxidizing 

 enzymes are very widely distributed. Since enzymes generally 

 seem to be produced by plants or animals for some definite 

 purpose in the life of the organism, it was natural that specula- 

 tion should arise regarding the function of the oxidizing enzymes. 

 Their usefulness to the plant probably lies in their power to act 

 as accelerators of the ordinary processes of oxidation as we shall 

 see in a closer study of their function in the plant. 



The oxidases, more especially peroxidase and occasionally 

 oxygenase, are found in seeds and seem to bear some relation 



