PERIOD VII. 1867 AND AFTER 19 



subject of study. Hesse and Zopf, and more recently Lettau, have been 

 engaged in the examination of those unique products, the Hchen acids, while 

 other workers have investigated lichen derivatives such as fats. Ecology of 

 lichens has also been receiving increased attention. Problems of physiology, 

 symbiosis, etc., are not yet considered to be solved and are being attacked 

 from various sides. 



British lichenologists since 1867 have been mainly engaged on field 

 work, with the exception of Lauder Lindsay who published after that date 

 a second great paper on the spermogonia of crustaceous lichens. Leighton 

 in his Lichen Flora and Crombie in numerous publications gave the lead in 

 systematic work, and with them were associated a band of indefatigable 

 collectors. Among these may be recalled Alexander Croall (1809-85), a 

 parish schoolmaster in Scotland whose Plants of Braemar include many of 

 the rarer mountain lichens. Henry Buchanan HoU (1820-86), a surgeon in 

 London, collected in the Scottish Highlands as well as in England and 

 Wales. William Joshua (1828-98) worked mostly in the Western counties 

 of Somerset and Gloucestershire. Charles Du Bois Larbalestier, who died in 

 191 1, was a keen observer and collector during many years; he discovered 

 a number of new species in his native Jersey, in Cambridgeshire and also in 

 Connemara; his plants were generally sent to Nylander to be determined 

 and described. He issued two sets of lichens, one of Channel Island plants, 

 the other of more general British distribution, and he had begun the issue 

 of Cambridgeshire lichens. Isaac Carroll (1828-80), an Irish botanist, issued 

 a first fascicle oi Lickenes Hibernici containing 40 numbers. More recently 

 Lett^ has reported 80 species and varieties from the Mourne Mountains in 

 Ireland. Other more extensive sets were issued by Mudd and by Leighton, 

 and later by Crombie and by Johnson. All these have been of great service 

 to the study of lichenology in our country. Other collectors of note are 

 Curnow (Cornwall), Martindale (Westmoreland), and E. M. Holmes whose 

 valuable herbarium has been secured by University College, Nottingham. 



The publication of the volume dealing with Lichenes in Engier and 

 Prantl's Pfianzenfantilien has proved a boon to all who are interested in the 

 study of lichens. Funfstiick^ prepared the introduction, an admirable 

 presentation of the morphological and physiological aspects of the subject, 

 while Zahlbruckner', with equal success, took charge of the section dealing 

 with classification. 



^ Lett 1890. '- Fiinfstiick 1898. •' Zahlbruckner 1903-1907. 



