510 SUMMARY OF CUIUIENT RESEARCHES RELATING TO 



Actinoptychus splendens (formerly Actinosplwiia splenclens) with 3 rays, 

 with a o-in. and D eye-piece on a dark ground, with a very low-power 

 condenser, say the back lens only of an Abbe, and a small stop, he will 

 see the aulax beautifully shown white. This diatom is an excellent test 

 for I, i, and 4-10 objectives when seen on dark ground ; the aulax 

 is now black, and should be clean-cut in all azimuths and quite sharp. 

 If ' N. E. B.' will also examine Hyalodiscus maxinms on a dark ground 

 with D eye-piece, he will see the six rays, and a Symholophora trini- 

 tatis gives 12 rays ; by this means the rays in other diatoms may be 

 detected." 



B. Technique.* 

 (1) Collecting Objects, including- Culture Processes. 



Collection of Bdelloid and other Rotifera.f — D. Bryce's notes are 

 intended to widen the interest of the pond-life worker who has hitherto 

 confined himself to collections by means of a net or of the simple 

 dipping. After a brief historical sketch of the work accomplished by 

 earlier British microscopists in connexion with Rotifera, he draws 

 special attention to C. F. Rousselet's various lists (published from time 

 to time in this journal) of species described as new since the publication 

 of Hudson and Gosse's well-known work of 1886-9. He points out 

 that while the greater proportion of these very numerous discoveries 

 have resulted from collections in areas not previously searched, quite a 

 large number of the new species have been found in habitats which are 

 more or less outside the activities of the ordinary collector, and more 

 particularly by the systematic examination of moss. The various 

 methods of collection are accordingly dealt with under the separate head- 

 ings of pond-work and moss-work. 



The former covers work in all water-habitats, whether standing or 

 running water, with the exception of bog-pools. In general pond -work 

 with a net, he finds it desirable to exclude from the catch as many 

 Entomostraca insect larvge, and water-worms as possible, and therefore 

 uses a double net, an inner of muslin of texture suitable to keep liack 

 such unwelcome intruders, and the outer of Indian silk, the latter fitted 

 with an easily detachable metal tube in place of the usual glass tube or 

 bottle. As auxiliary methods he describes, among others, the squeezing 

 of handfuls of Conjervae into the net, the " washing " of water-plants, 

 the gathering of any growths on submerged stone or wood, and the 

 examination of Asellus and other possible hosts for parasitic forms. 



Under moss-work he recalls that certain species of Bdelloid Rotifera 

 had been found in moss by Ehrenberg, but the references thereto escaped 

 attention, being subsequent to his widely known work of 1838. That 



* This subdivision contains (1) Collecting Objects, including Culture Pro- 

 cesses ; (2) Preparing Objects ; (3) Cutting, including Embedding and Microtomes ; 

 (4) Staming and Injecting ; (5) Mounting, including slides, preservative fluids, etc. ; 

 v(6) Miscellaneous. 



t Journ. Quekett Micr. Club, xiii. (1917) pp. 205-30 (2 figs.). 



