28 Transactions British Mycological Society. 
of the wood cells by the fungal hyphae, thus causing wilting 
and death of all parts above the point affected. 
(5) No differences in power of infection or in behaviour in 
culture were observed between strains of the fungus isolated 
from different sources. 
I should like to take this opportunity of thanking Mr F. T. 
Brooks for the time he has spent in directing the work and for 
many suggestions and criticisms, and Professor Seward for 
laboratory accommodation. 
REFERENCES. 
(1) Mayr, H.—Uber den Parasitismus von Necivia cinnabarina. Unters. aus 
d. Forstbotan. Institut. zu Miinchen, 111, pp. 1-6 (1883). 
(2) WeHMER, C.—Zum Parasitismus von Nectria cinnabarina Fr. Zeitsch. f. 
Pflanzenkr. Iv, pp. 74-84 (1894). 
Einige weitere Beitrage zum Parasitismus der Nectria cinnabarina 
(Td.) Fr. Ibid. v, pp. 268-276 (1895). 
(3) Duranp, E. J.—A disease of currant canes. Cornell Univ. Agric. Exp. 
Stat. Bot. Div. Bull. 125, pp. 21-38 (1897). 
Other references to literature will be found in the 3rd edition of P. Sorauer’s 
Handbuch der Pflanzenkrankheiten, 11, p. 205 (1906). 
ORCHID MYCORRHIZA*. 
With Plates II—VII. 
By J. Ramsbottom. 
INTRODUCTION. 
One of the most interesting phenomena in biology is that 
generally known as symbiosis—the living together of two organ- 
isms in close association. It is usually considered that this 
intimate relationship is of benefit to both components. Many 
examples occur in the plant kingdom. The lichen is probably 
the best known of these, being a composite plant formed of a 
fungus and an alga in definite union. Other well-known examples 
are the bacteria (Pseudomonas radicicola) living in the root 
nodules of Leguminosae, and the Ginger-beer plant}, of which 
the lumps are composed of a yeast (Saccharomyces pyriformis) 
and a bacterium (Bacterium vermiforme). An intimate union can 
also occur between plant and animal, as in the case of the marine 
worm Convoluta, in the body of which an alga is always present, 
* Reprinted from Messrs Charlesworth and Co.’s Catalogue, 1922. The 
Editors desire to thank Messrs Charlesworth for permission to reprint this 
article and for the loan of the blocks. 
+ The Ginger-beer plant is, at the present time, being widely distributed 
- over the country as ‘Californian Bees,’’ ‘‘Macedonian (Salonika) Bees,”’ 
“Mesopotamian Bees,” ‘‘ Palestine (Jerusalem) Bees,’’ “Wine Bees,” “ Water 
Bees,’”’ ‘‘Balm of Gilead,” etc. 
