(425 ) 
The fungus is thus seen to bear the same general relation 
to the higher plant as that observed by one of the authors in 
numbers of mycorhizal species. The vegetative part of the 
fungus coats the surface of the root sending out branches 
into the substratum, and organs of interchange into the epi- 
dermal cells of the higher plant. In Cora/lorhiza and allied 
forms the mycelium or vegetative part of the fungus lives in 
the outer cortical layers, sending out the two kinds of branches. 
In the closely related family of the Pyrolaceae the epidermal 
cells are enlarged to such an extent that they occupy half the 
radius of the root and serve to shelter the mycelium of the 
symbiotic fungus, and its organs of interchange. 
t is noteworthy that Afonotropa has been under investiga- 
tion for sixty years and that the identity of the symbiotic 
fungus is still unknown, or not clearly established. Fries 
named it Zudurcenia Alonotropae, on an external examina- 
tion but he did not place it with the species of the genus 
which have since been included in the Ustilaginae, and he 
thought later that it resembled the conidial forms of Sepe- 
dontum, Fustdium, or Zygodesmus (2,3). Ryland described 
the manner of the occurrence of the ‘‘ byssoid fungus” on the 
roots of Vonotropa, and M. J. Berkeley recognized A pz- 
phagos Luxfordti, Zygodesmus Berkely7, and Sepedonium 
Wolsont, Cladosporium Leest in the Jayer sheathing the 
roots (7). The authors have found a perithecium resembling 
that of the Pleosporiaceae in the meshes of the fungus of 
Hypopitys, and MacDougal detected conidial branches like 
those of Penscillium on Prerospora. A series of careful cul- 
tures would be necessary to establish the identity of the 
fungus in each instance as well as in all symbiotic associa- 
tions of this character. It is not improbable that different 
species will be found to adhere to the forms under discussion 
in different localities. 
The changes ensuing in these roots with age, are of the 
greatest interest. An exfoliation of the epidermis carrying 
with it the mycelial layer is very marked in Sarcodes and 
Pterospora, and is sometimes seen in //ypopitys and ALono- 
