COLONIES OF NITROGEN-GATHERING BACTERIA ON A LEAF 



The small daik spots \isible on the under surfaee of this leaf are ncdules containing 

 colonies of a non-motile i:i.rogen-fixing baeteiium similar to the one which inhabits 

 the ncdules on the roots of leguminous plants, and which makes the peas, beans 

 and vetches valuable as green-manures or sources of plant food. These ncdules 

 have been found on the leaves of several tropical plants, and the question arises, 

 Will it not be ])ossil)le to use these species in the same manner as the legumes ? (Fig. 



