347 
“who made ‘the’ interesting discovery that the Bacteria of the 
nodules are capable of fixing free nitrogen from the air. The 
plants investigated were four species of \Pavetta and one ‘species 
of Psychotria (P. bacteriophila Val.). 
It appears that the presence of Bacterial nodules is a constant 
feature of those species in which they have been found, and the 
explanation of this is supplied by von Faber, who demonstrated 
the occurrence of Bacteria in the seed, between the embryo and 
the endosperm. The seedling is therefore infected from the first. 
The Bacteria establish themselves in the leaf-buds, in a gummy 
secretion within the stipular sheath, and infect the young leaves in 
the bud, entering them through certain stomata, which are 
formed at a rather early stage and are connected with secretory 
cavities in the mesophyll. In the region of each point of entry 
of the Bacteria, the mesophyll develops into a special enlarged 
lacunar tissue, the intercellular spaces of which become occupied 
by the Bacteria, the leaf becoming locally thickened owing to the 
special growth of mesophyll-tissue. © 2... 
The Bacterium of the nodules, which has been named Myco- 
b 
(of Pavetta Zimmermanmana, Val.) free from Bacteria, and 
consequently. without typical nodules, and afterwards induced the 
seedlings, one having Bacterial nodules, the other not, and 
poth being grown on a substratum containing no nitrogenous 
comp 
9 Ce ed 
high percentage of nitrogenous substance. The suitability of 
such leaves for use as green’ manure therefore suggests itself, and 
