322 C. F. ROUSSELET ON 



and now obtainable at a firm of mill furnishers in Mark Lane, 

 Bryan Corcoran & Co. This material lasts much longer and does 

 not clog or shrink so much as the former. The shape of the ring 

 net has always been the same as long as I am able to remember 

 it ; its size 6 x 5J inches wide, 6 inches long. The little bottle 

 I devised myself, making it 3J inches long by 1| inch wide, of 

 clear crown glass with a rimmed edge at one end. It was made 

 for me by a glass-blower of High Holborn named Mliller.* 



When out collecting I used to fill one or two large square 

 bottles, and on arriving home I emptied their contents into a 

 couple of parallel-sided aquaria of various and suitable sizes. 

 These aquaria appear to have been first introduced by Thomas 

 Bolton, of Birmingham, and were exhibited by him at the 

 International Fisheries Exhibition held in the year 1881:, at South 

 Kensington. The size was originally 6 inches by 1 inch in depth 

 from back to front, which I considered rather too small, so I 

 had some constructed of a slightly larger size, 7 inches by IJ. 

 which answered admirably. 



About 1889 I invented a tank microscope with an arm carrying 

 an aplanatic 6 mm. lens, so jointed that the lens could be moved 

 at pleasure parallel with the glass front of the tank and having 

 focusing adjustments by rack and pinion. At first this appara- 

 tus was fixed by screw-clamp to the tank itself, but afterwards 

 Mr. Charles Lees Curties suggested that it should have a separate 

 wooden base to enable me to replace one tank by another wlien 

 desired, without having to shift the clamp. 



After a few hours' "rest" all the impurities and debris hud 



* The same glass-blower made for me two kinds of glass pipettes: 

 (1) Fairly strong glass tube l-^% inch in width, 8 inches in length, with 

 the end drawn out gradually from the middle, for use with a red non- 

 perforated indiarubber teat (obtainable from Messrs, Baird & Tatlock, 

 of 14, Cross Street, Hatton Garden, E.C.); (2) Finer tube, 6-8 inches 

 long, with a funnel-shaped head, to be covered with thin indiarubber 

 membrane (such as is used to repair the inner tubes of cycle tyres), 

 by means of which single Rotifers, or a few, can be picked up by the 

 varying pressure of a single finger on the membrane and so trans- 

 ferred to wherever may be desired. 



