OCCURRENCE OF UREASE IN LEGUME NODULES. 79 



Cucumis melo, L. Cucurbita moschata, Duchesne 



(Rock Melon) (Cattle Pumpkin) 



Abrus precatorius, L., very 

 active. (Crab's Eye) 



Other plant parts which were found to give a reaction 

 for urease were: — 



Ovules and pollen of a Hippeastrum. 



The tubercles, rootlets and bulb of Macrozamia 

 spiralis, Miq. 



Dried immature leaves of a Wistaria. A measure- 

 ment made of the activity of these showed that 

 1 gram of the dried leaf was capable of decom- 

 posing '3 grams of urea in 16 hours. 



Crushed dried remains of the following also reacted for 

 the presence of the enzyme, the reaction obtained with 

 the lichens being particularly pronounced and rapid. 



A red Alga (saprophytic) from old fence. 

 A green Alga „ „ 



Ramulina yemensis, a gray lichen. 

 Xanthoria parietina, a golden lichen. 

 Usnea barbata, a lichen. 



Although no conclusions as to the part which this enzyme 

 actually plays in the economy of the plant can be drawn 

 from the above observations, the fact that it has been 

 detected in parts in which symbiosis occurs and in other 

 parts in which active metabolic changes are doubtless in 

 progress, as in pollen, ovules, young leaves, etc., seems to 

 suggest that some correlation may exist between its 

 presence and those processes of elaboration and interchange 

 of nutritive material which must be constantly occurring 

 in the living plant. 



