QUEKETT MICROSCOPICAL CLUB. 655 



a 1/2-in. dry lens is converted into a l/3rd-in. immersion system 

 of much improved denning power." 



Mr. G. T. Harris, of Sidmouth, formerly a member of the 

 Club, had presented to the Cabinet 72 micro, preparations of 

 various mosses. He accompanied them with a paper on " Micro- 

 scopical Methods in Bryological Work," which was read by 

 Mr. F. J. Perks. It was pointed out that mosses did not appeal 

 very strongly to microseopists per se, as the work to be done 

 with them is mostly systematic, and they yield but few " dis- 

 play " objects. The earlier bryologists relied mainly upon 

 herbarium sheets for the preservation of their specimens and 

 for identification purposes a plan sufficient at a time when the 

 division of the group into species, sub-species and varieties was 

 not carried out to the extent it is now. Thirty years ago specific 

 distinctions were largely dependent upon general habit and the 

 presence or absence of the so-called " nerve " and the nature of 

 the leaf margin. But no bryologist of the present day would 

 care to decide upon specific names without microscopic assist- 

 ance. The impossibility of securing the perfect cleanliness so 

 desirable in microscopical mounts with moss specimens was 

 pointed out, the plants growing usually in mud, or dirty situa- 

 tions, and, owing to their fragile constitution, not bearing any 

 cleaning process without damage. Probably most bryologists 

 relied on glycerine jelly for mounting. Some years ago Mr. 

 Harris prepared a considerable collection of Hypnaceae in this 

 medium, but in about twelve months found the whole of them 

 so deteriorated as to be of no value. As in other instances the 

 result had been successful, he concluded the difficulty arose 

 from avoidable causes. In his paper he gave various precau- 

 tions that should be observed in using glycerine jelly. Farrant's 

 medium probably comes next to glycerine jelly in usefulness ; 

 it is very convenient to use, and, of course, allows of great delibera- 

 tion in arranging the object. For peristomes, which require 

 to be examined by transmitted light, it is excellent. Other 

 mediums having various advantages were then referred to, 

 particularly two, having copper acetate in their composition, . 

 one with glycerine and the other with potassium acetate ; for- 

 malin was also noticed. Cases in which difficulty arose owing 

 to the dark colour and want of transparency of the leaves, and 

 where manipulation was not easy owing to structure, were noted, 



