Endotrophic Mycorhiza of Ericacecz. 225 
Fio. III. (1) Stem tubercle. (2) Transverse sections of normal stem, 
along plane § 7 r in 1. (3) Transverse section of stem tubercle, along plane <pz 
in 1. x., phloem ; /., fibres ; end., endodermis (crowded with starch in 2, no 
starch in 3) ; c., cortex, e., epidermis ; s., fungus forming spores in cortex of 
3 x', hypertrophied phloem infested by fungus. 
only one (or in any case only a few) comes to seed. It may be 
supposed that the necessary adjustment between the endophyte 
and the cells of the ovary is only reached in a comparatively few 
cases. 
When any of the organs of Arbutus dry up, the fungus, in 
these parts, cannot grow any longer as an endophyte, and has to 
resume the life of a saprophyte. This is a normal occurrence 
on the corolla and stamens of the Arbutus flower, as these parts 
