LIBRARY 
NEW YORK 
BOTANICAL 193 
GARDEN 
RECENT WORKS ON LICHENS. 
By A. Lorrain Smith, F.L.S. 
In the following pages, a summary is given of publications 
that were unavoidably omitted from the handbook “ Lichens,”’ 
and that have appeared since the manuscript was handed to the 
press in the beginning of 1920. During the war-years and for 
some time after, it was difficult or impossible to get hold of the 
works of continental botanists. A different apology is due in 
the case of Sernander’s ecological works: in that case it was the 
language difficulty that barred the way at the time. 
Two valuable papers dealing with recent literature appeared 
in 1921: one by Bioret which reviews lichenological work from 
Igio to 1919; and one by Paulson which is a résumé of British 
Lichenology from IgII to 1920. 
In this survey purely systematic publications have not been 
included: these are both numerous and varied; the essential 
work of knowing and classifying the plants has not been neg- 
lected. It may, however, be permitted to direct attention to 
Bernt Lynge’s (1921) Studies of Norwegian Lichens, full of 
helpful notes, to the Handbook of British Lichens by A. Lorrain 
Smith (1921) which provides a key based on the Monograph of 
British Lichens, and to W. Watson’s Determination of Lichens 
in the Field (1922), a key to the genera and to many species 
of common British lichens based on field characters and in- 
tended to be of service to field botanists especially in their 
study of ecology. 
LICHEN GONIDIA. 
Several writers have dealt with the types of gonidia present 
in the lichen thallus, and with their behaviour in culture media. 
Letellier (1917), a pupil of Chodat, has devoted himself especially 
to this research. He isolated a Nostoc from Peltigera sp., and 
in culture he found that nitrates and ammonium salts were 
utilized by the alga but not peptone or glycocol. Glucose and 
sugars generally favoured growth, a result opposite to that 
obtained by Chodat and others with free Cyanophyceae. Eva 
Mameli (1920) in her chemical study of the blue-green lichens 
decided that in the lichen thallus the algal constituents suffered 
no important change except occasionally in the size of the cells. 
Linkola (1920) has cultivated Nostoc gonidia from eight different 
species of Peltigera: they grew well and formed hormogonia 
which developed into spores or into Nostoc colonies. Linkola 
refers them all to Nostoc punctiforme Hariot. The only variation 
M.S. 13 
