222 DAVID BRYCE ON THE 



If these fine particles are not removed from the water, the 

 stock goes quickly sour and every rotifer present is poisoned. 

 It is therefore essential that the water should be cleared ; and 

 this process, and the time which elapses before the rotifers regain 

 activity, constitute the main differences in the treatment after 

 collection of dry mosses as compared with that of wet mosses, 

 such as Fontinalis or Sphagnum. 



The moss is placed in a wide-mouthed bottle which is then 

 filled nearly full with water. The capacity of the bottle may 

 range from two ounces upwards according to the quantity of moss 

 to be dealt wdth and its condition as regards adherent dirt. 

 Clean mosses such as are gathered in woods and from tree 

 trunks can be washed in larger quantities than short-stemmed 

 mosses from the ground or from walls. As a rule, the moss 

 should not more than cover the bottom of the bottle. When it 

 has become thoroughly soaked, the moss is well stirred about 

 and removed. The water in the bottle is allowed to settle for 

 two minutes, in which time all sand and all rotifers will fall 

 to the bottom, leaving the water more or less cloudy or even 

 opaque. Some two-thirds is to be carefully poured away, and 

 the bottle refilled. The procedure is repeated until, on refilling, 

 the water is not perceptibly cloudy. After another two minutes 

 the greater part is poured away, leaving only a remainder to be 

 searched through as already described. A stock prepared in 

 this way will generally keep in good order for some weeks, giving 

 time to make a very thorough examination of the material, if 

 it is found to be productive. A simpler plan is to place some 

 moss in a bottle with a little water, and after allowing time for 

 the rotifers to revive, to shake the bottle and then pour off the 

 water into the stage trough. This plan answers quite well up 

 to a point with fairly clean moss, but according to my experience 

 the stock does not keep nearly so well as that which has been 

 systematically cleared. 



The sandy sediment which collects in roof-gutters, whether 

 in town or country, nearly always harbours some species of 

 Bdelloid Rotifera, and these can be secured by treating the 

 sediment in the same way as dry mosses. In town samples the 

 stock is usually very foul, and the water has to be changed many 



