PRESERVATION OF DESMIDS. 17 



somewhat plentifully, growing among tlie algae on the rocks, 

 and associated with it large numbers of Netrium Digitus. It is 

 obvious that the ring-net is of little use in such localities ; the 

 better way is to collect a tuft of algae by hand and wrap it in 

 waterproof paper or place it in a tube filled with the water in 

 which it grows. 



If the collecting excursion be one of a day's duration only, the 

 ordinary supply of tubes and bottles will suffice for all the material 

 likely to be collected, and it may be brought home in the water 

 in which it was found ; but with an extended excursion away 

 from home the number of bottles and tubes necessary for several 

 weeks' collecting would mean a considerable amount of very 

 careful packing. In addition, to bring home the bottles filled 

 with the miscellaneous gatherings that are more or less inevitable, 

 would be to invite certain disaster. Aquatic larvae will intrude 

 into gatherings of desmids, and when bottled will die, and when 

 dead will decompose, and the opening of such a collection at home 

 some weeks later is not a fragrant operation. When planning a 

 collecting trip of some five or six weeks' duration over Dartmoor 

 I duly considered these drawbacks and sought some way of 

 obviating them. After considering and rejecting several methods 

 I decided to preserve the gatherings on the spot. My object was 

 to work a certain district of the moor thoroughly, and to keep 

 the gatherings as far as possible separate. The method I finally 

 adopted, and which gave me complete satisfaction, was to obtain 

 material from each bog, moor-pool, etc., and kill and fix the 

 plants (and incidentally what was with them) on the spot. The 

 details of this method may be of interest, and possibly of use, to 

 some of the members. 



A small funnel to support the filtering material is essential. 

 This may be of ebonite, or tin ; glass is inadvisable. For my 

 own use I make them out of a piece of " ferrotype " metal, cut 

 to the shape of the collector's net ; three small holes cut in one 

 side and three metal buttons fixed on the other enable the piece 

 of metal to be converted at once into a filter support, which un- 

 buttoned when not required becomes again a flat piece of metal 

 occupying little space in the collecting-case. After trying many 

 materials for filtering purposes I found nothing so good as chamois 



JouRN. Q. M. C, Series II.— No. 78. 2 



