356 Ward. — Recent Publications bearing on the 
the question as to whether the fungus of the Leguminosae 
aids in the fixation of free nitrogen, and we cannot regard 
it as proved that the fungi of Frank’s Mycorhiza take any 
part in providing the plant with nitrogenous elements, how- 
ever probable it may appear. Moreover, I may suggest that 
the cases are not quite similar : in Frank’s observations 
the fungus may merely hurry the decomposition of organic 
remains. With respect to the alleged absorbent function — 
or root-hair function — of Frank’s fungi, it is only necessary 
to point out that it is difficult to imagine how a fungus hypha 
with its low and peculiar organisation can assume the remark- 
able and by no means simple functions of root-hairs : the 
anatomical facts are in Frank’s favour, so far as they go, in 
reference to the Cupuliferae, but of course it is always 
hazardous to attempt to explain physiological problems 
simply on anatomical evidence. 
With respect to Vicia Faba , there are no reasons for 
supposing that the fungus replaces the root-hairs functionally 
in any way ; the experiments of Hellriegel, Frank and Vines, 
point to the possibility of its aiding in rendering nitrogen 
available, in some way as yet unexplained ; and my own 
observations point to the probability that it stimulates the 
roots to absorb and use whatever nitrogenous materials are 
present with extraordinary avidity. One consequence of this 
is, no doubt, increased respiration, — i. e. a more rapid rate of 
absorption of the oxygen in the soil ; but whether we can 
go further than this needs investigation, though it may have a 
bearing upon Deherain’s suggestion. 
As regards the Leguminosae, therefore, we are still face 
to face with two distinct problems, quite independent of 
the old one as to the parasitic nature of the tubercles, which 
has been solved by my discovery of the causal fungus entering 
the root-hairs and stimulating the root-cortex locally. These 
two problems are: (i) Does the fungus in question directly 
co-operate in the absorption of food-materials from the soil, 
nitrogenous or otherwise? and (2) Does the fungus take any 
part in the preparation of nitrogenous substances, or the 
