226 DAVID BRYCE ON THE COLLECTION OF ROTIFERA. 



Monostyla cornuta and Distyla inermis will live for a few days if 

 some fragments of plants, etc., are left in the cell to provide 

 some food for them. Nearly all the moss-frequenting Bdelloida 

 will live for at least a month under the same conditions, but 

 the larger pond-dwelling species of the genus Rotifer seldom live 

 more than a few days. Hitherto I have not supplied the cap- 

 tives with food to supplement that present in the cell, merely 

 replacing when necessary the water lost by evaporation. I am 

 now experimenting upon the results attainable by the supply 

 at intervals of small quantities of microscopic algae of the 

 nanno-plankton type, but so far with indifferent success. 



The method I have indicated of placing the droplet of water 

 (containing the rotifer) near the centre of the cell, and on no 

 account permitting the fluid to extend to the cell-wall, is so far 

 effective in retarding evaporation that even during summer 

 temperatures the cells can be left in any cool place from one 

 day to another without danger to the contents. For longer 

 periods it is desirable to store the cells in a " damp chamber." 

 That which I use (fig. 2) consists of three parts : an ordinary 

 bell glass of about 7J inches diameter and 8 inches high, a 

 shallow basin of about 8 inches diameter at the bottom and a 

 staging of galvanised wire (fig. 2, d), on which there is room for 

 some thirty glass slips laid horizontally. The bottom of the dish 

 is filled with water and old moss. In this chamber I have re- 

 peatedly kept cells undisturbed for more than three weeks, 

 without their contents being dried up or the captive rotifers 

 killed. 



The advantages offered to the student of Rotifera by the 

 use of these cells, etc., for winter work scarcely need to be pointed 

 out. At a season of the year when it is difficult to screw up one's 

 courage to a long tramp to a distant and desolate pond, one 

 can have resort to the mosses stored up from more pleasant 

 summer excursions and from them obtain animals which will 

 interest and repay repeated examination. 



I conclude these notes with figures of various pieces of 

 apparatus which I find useful, and particulars of their con- 

 struction in so far as they are of home manufacture. 



The Hardy flat bottle (fig. 1, a, b) is in the form of an elongated 



