428 SUMMARY OF CUEEENT EESEAECHES llELATING TO 



gives the date of collection and the methods of examination employed 

 in his research. He describes the mature gonidium. the breaking up 

 of the contents into two, four, eight, sixteen or more daughter gonidia. 

 He concludes that the gonidium of these lichens is a species of CfiloreUa. 



A. L. S. 



Review of Publications on Lichens. — G. Bioeet (Rev. Gen. Bot, 

 1921, 33, G3-76, 146-60, 214-20, 2G4-72, 328-36, etc.). The author 

 has discussed the many publications on the nature and development of 

 lichens that have been published since 1910. x\.n account of each 

 paper arranged under different subjects is given, with the criticisms of 

 the various works, and the author's own considered views. Finally, 

 Bioret has listed all recently published works under a series of subjects, 

 and geographically under the different countries where the papers have 

 been published. His work shows at a glance the v^ide interest in 

 lichens and the importance attached to the study of the group. A. L. S. 



Lichens. — A. Lorrain Smith {Cambridge Botanical Handhoolcs, 

 1921, xxii and 464 pp., 135 figs.). The Avriter gives a connected 

 account of lichens from their earliest mention up to the present day. 

 Special stress is laid on the symbiotic nature of the lichen thallus, and 

 on the interaction of the symbionts, alga and fungus, and on the 

 structure formed by them. Other subjects dealt with are their reproduc- 

 tion, physiology, bionomics, ecology, and the economical value of the 

 plants. There is also a survey of classification, largely drawn from the 

 work of A. Zahlbruckner, the leading exponent of lichens, whose work 

 on systematy has been followed, as it is likely to hold the field for some 

 considerable time. Glossary, bibliography and index complete the book. 

 The illustrations are, manv of them, photographs of the living plants. 



A. L. 8. 



Ten Years' Progress in Lichenology in the British Isles. — 

 E. Paulson {Essex Naturalist, 1921, 19, 273-86, 4 pis.). The author 

 reviews recent work on British lichens, which he arranges under four 

 heads : Records, Ecology, Morphology, and Physiology and Symbiosis. 

 The largest number of papers deal with Records of Species. Consider- 

 able attention has been given to ecology, and symbiosis is treated from 

 different points of view. Connected with the latter subject is the 

 behaviour of the algfe that form the gonidia of the thallus. The author 

 gives results of his own discoveries of the healthy sporulation of the 

 lichen algte within the thallus. Dr. Church's views on the origin of 

 lichens ai-e also discussed. A very full biblio2:raphy is appended. 



A. L. S. 



