18 G. T. HARRIS ON THE COLLECTION AND 



leather. Even the filter papers specially made for filtering under 

 pressure proved useless after a little use. Chamois leather has 

 the great advantage that it allows of the residue being entirely 

 removed with a spatula without the risk of tearing it and thus 

 losing part of the collection. Any material that I have tried 

 becomes slow in action when thoroughly saturated with water, 

 and for this reason, if considerable collecting is done during the 

 day, two, or even three, filters in operation at the same time are 

 not too many. At least this was my experience when collecting 

 on Dartmoor. My collecting-case for a day's work contained a 

 dozen 3 in. by 1 in. tubes, the corks numbered in large numerals 

 of white paint 1 to 12. Smaller tubes also were carried, and 

 several 4- ounce wide-mouthed bottles. A blunt- edged knife or 

 spatula for scraping of! the residue was also carried, and a small 

 supply of waterproof envelopes, about " court " size, for containing 

 tufts of algae. The ring-net for bog collecting is indispensable, 

 but after breaking six tubes in one day's collecting against sub- 

 merged and hidden stones, I substituted for the glass tube attached 

 to the net a zinc one. It really is not necessary to examine the 

 contents with a lens, as it would be quite impossible to make any 

 useful determination of the smaller species. On arriving at the 

 bog I propose to work I select a suitable furze or heather bush 

 contiguous to the bog and support my filter funnels securely in 

 the topmost twigs so that drainage from the filters is unimpeded. 

 The bog is now worked with the net and each tubeful collected 

 transferred to the filters. Tufts of sphagnum may also be col- 

 lected and the bog water contained in them squeezed into the 

 filter to extract any desmids growing amongst them. When 

 sufficient has been collected the residue is drained, then scraped 

 off the chamois leather with the spatula and transferred to one 

 of the numbered tubes ; the name of the bog and whatever details 

 are deemed necessary being entered against a corresponding 

 number in a notebook. After the residue has been placed in 

 the tube, clear bog water is added and about 4 c.c. (for a 3 in. by 

 1 in. tube) of the following killing and fixing solution : 



Cupric sulphate (10-per-cent. solution) . . . 100 c.c. 



Mercuric chloride (saturated solution) ... 10 c.c. 



Exactitude in the amount of preservative added is unnecessary, 



