1921| CURRENT LITERATURE 4II 
Beloglottis, Mesadenus, Pseudogoodyera, Brachystele, Schiedeella, Trachelosiphon, 
Deiregyne, Gamosepalum, Funkiella, Cladobium, Coccineorchis, Lyroglossa, 
Pteroglossa, and Centrogenium. 
STAPF" has established a new genus (Daturicarpa) of Apocynaceae from 
the Belgian Congo. It belongs to the Tabernaemontaneae, and includes 
three species of shrubs.—J. M. C. 
ClasSification of symbiotic phenomena.—McDouGALt” has written a 
very sensible and stimulating article on symbiosis and its subdivisions. Very 
properly he disapproves of the numerous restricted definitions of the term, 
going back to the original definition of DEBAry, which happens also to be the 
only definition that justifies the retention of the word in the literature, and the 
only definition that is etymologically correct. It is one of the curiosities of 
biological science that so many writers have used the term symbiosis in the 
sense of mutualism, a relationship that does not exist; and even if it did exist 
we should not need two terms for the same relationship. The term is much 
needed, however, in the original and correct sense of “the living together of 
dissimilar organisms,” as pointed out by McDoucatt, for there is no other 
erm of such broad and general nature. The author’s primary division of 
symbiosis is into disjunctive and conjunctive, each in turn being subdivided 
into social and nutritive; each type of nutritive symbiosis may be further sub- 
divided into antagonistic and reciprocal. Plant communities illustrate social 
disjunctive symbiosis; lianas and epiphytes illustrate social conjunctive 
symbiosis. Antagonistic disjunctive symbiosis is illustrated by herbivores and 
plants; antagonistic conjunctive symbiosis is illustrated by the ordinary cases 
of parasitism, such as plant diseases, ectotrophic mycorhizas, etc. Recip- 
rocal disjunctive symbiosis is illustrated by flowers and pollinating insects, 
— conjunctive symbiosis by cases of reciprocal parasitism, such as are 
seen in lichens, root tubercles, and endotrophic mycorhizas. McDovuGALi 
condemns the eiioes view of some botanists that lichens are simply fungi. 
He asserts that it is just as absurd to call a fungus-alga combination a fun- 
gus as it would be to ges the term fungus to the mycorhizal combination of 
roots and fungi.—H. C. Cowles. 
Forests of British Columbia,—WuitForD and Craic have published 
an admirable volume on the forests of British Columbia, which are among the 
most interesting forests in existence. The report is based on three years of 
= Srapr, O., Daturicarpa, a new genus of Apocynaceae. Kew Bull. no, 4. 166- 
171. figs. 2. 1921 
12 ipetiodudti: W. B., The classification of symbiotic phenomena. Plant World 
21:250-256. 1918. 
3 Sat H. N., and Craic., R. D., Forests of British Columbia. Rept. 
Comm. Conserv. Canada, Committee on Forests. pp. 409. pls. 28. maps 21. 
Ottawa. 1918. 
