338 Ward. — Recent Publications bearing on the 
Frank’s second conclusion is (2) that the root and the 
fungus increase together ; as the root-cells divide, the fungus 
passes forward cell by cell. (3) The fungus is strictly con- 
nected with that part of the plant which absorbs the food- 
materials. (4) The orientation of the cells which contain 
the hyphae is such that they must necessarily act as the 
go-between for the absorbed substances and the conducting 
paths of the root. (5) Those orchids which are devoid of 
chlorophyll- and which therefore depend on the humus of 
the soil for carbonaceous matters — always have this form of 
Mycorhiza, and highly developed. 
We are therefore to regard the Mycorhiza as a humus- 
absorbing organ. 
It is thus evident that, according to Frank’s latest pub- 
lications, the idea of Mycorhiza is to be extended to all 
such cases as that investigated by Wahrlich, and it follows in 
the opinion of several botanists that the root-tubercles of the 
Leguminosae will have to be included as another example ; 
for, as I have lately shown 1 , we have here an exquisite example 
of symbiosis between a fungus and the root. It is of course not 
to the purpose to enter here into details about this case, but I 
wish to point out how decidedly the facts observed are op- 
posed to Frank’s view that the fungus acts as root-hairs 
or absorbent organs to the bean. Of course, it may be 
replied that on this account it must be excluded from the 
category of Mycorhizae ; if this is allowed, I think the same 
will follow as regards several of the others. The case of the 
fungus in the roots of J uncus bufonius 2 will also have to be 
taken into account in this connection, as well as a very 
remarkable example in Podocarpus , which I have lately 
observed and am at present investigating. And there are 
other instances also. 
The point on which stress is to be laid at present is that 
in the bean (1) the mycelium of the fungus stimulates the 
1 £ On the Tubercular Swellings on the Root of Vida FabaC Phil. Trans., 1887 , 
PP- 539-562. 
2 See Bot. Zeit. 1884, No. 24. 
