644 PEOCEEDIKGS OF THE SOCIETTl'. 



of the economy of Nature ; there was no loss at all, no wave-length 

 except that definite one which the organism had use for. There was no 

 example in commerce or in the Arts comparable in which the production 

 of light of one wave-length had been achieved without accompanying 

 wave-lengths which were not particularly wanted. 



Mr. Scourfield suggested spectroscopic examinattou of the reflected 

 light, with a view to the elucidation of the problem ; and the Chairman 

 agreed that such examination would settle whether reflection was a prime 

 factor in the phenomenon. 



Mr. Scourfield was cordially thanked for his exhibit. 



Mr. Wilson, who exhibited six species of MicrasUrias, said the genus 

 was a small one, and included some eighteen •British species and a few 

 varieties. Three species were found by the late James Murray only in 

 the Scottish lakes ; and while six species were very rare, six other species 

 might be classed rare, and the remainder were confined to certain 

 localities. They were found in the bogs and lakes among the hills of 

 the older Palaeozoic rocks, chiefly in the Highlands of Scotland, the 

 Cumberland Hills, and North Wales. Of the more common species, 

 M. rotata was abundant in some of the Epping Forest pools, and M. denti- 

 culata so plentiful on Sheen Common as almost to tinge the water green, 

 as in the bottle exhibited. 



Mr. Wilson was cordially thanked for his exhibit. 



Mr. Paulson presented a Report on Biological Work at Ruhleben 

 (with slides), compiled from letters written to him by Dr. A. E. Lech- 

 mere, Lecturer in Mycology, University of Bristol, and Mr. Michael 

 S. Pease, B.A. Cantab., both of whom are at present interned in the 

 Camp. 



On the motion of the Chairman a vote of thanks for his report was 

 accorded to Mr. Paulson. 



Mr. Martin Duncan exhibited a series of lantern slides illustrating 

 the paper he had communicated at the October meeting of the Society, 

 and tracing the life-history of OrpuUna. 



Messrs. E. Heron-Allen and Arthur Earland read a paper on varia- 

 tion in the arenaceous rhizopod Thurammina papillata Brady, based on a 

 study of many thousands of specimens dredged by the Scottish Fisheries' 

 Cruiser " Goldseeker " in the North Sea and North Atlantic. They 

 regarded all hitherto recorded species of Thurammina and Thurammi- 

 nopsis as varieties of the original type Thurammina papillata Brady, 

 and as having no biological significance. For taxonomic reasons most 

 of the specific names were retained with varietal values, and certain new 

 varietal names were proposed for forms not previously separated or re- 

 corded. The life-history of the genus was for the first time worked out. 



