528 PKEPARATION, MOUNTING, AND COLLECTION OF OBJECTS 



of the ease with which its leaves can subsequently be placed under the 

 microscope. Anacharis is much more difficult of manipulation, and 

 I mostly only take it now to aerate my aquaria. 



* In placing a weed in the flat bottle, do not put in more than one 

 branch at a time, otherwise the branches will only obscure each other 

 and render examination more difficult. 



' When searching for Polyzoa, such as Lophopus, Plumatella, 

 Fredericella, it is advisable to examine the rootlets of trees growing 

 at the edge of the water, and also to drag up weeds from the middle 

 of the pond or canal by means of a loaded hook and line. 



' A good collection thus made is transferred to small aquaria 6 to 

 8 inches high, 5 to 6 inches long, and 1 to 1J inch wide ; these we 

 have used for at least ten years and can attest their great value in 

 making the best possible use of a good day's collecting, and studying 

 in the most intelligent way the objects collected. f 



' Rotifers can generally be kept a week or a fortnight, some 

 species much longer ; their lives, as well as those of Polyzoa, can be 

 prolonged by feeding them about twice daily with a green soup 

 made by crushing some anachari^, or other green weed, in a small 

 mortar in a little water, which is then filtered through muslin. 

 They can be seen to feed on this under the microscope, their tiny 

 stomachs soon becoming filled with little balls of chlorophyll. 



' Under favourable conditions Melicerta, Stephanoceros, the Flos- 

 cules, and also Asplanchna, and other forms, breed and multiply in 

 the aquarium, and can then be preserved for a considerable time. 

 A little mud taken from a pond in winter or early spring, and 

 put in a tank at home, will often produce an unexpected number 

 and variety of rotifers and infusoria, which are hatched from 

 winter eggs and dormant germs. ' l 



There must of course be a balance in every tank between the 

 animal and vegetable life, or aeration must be artificially maintained. 

 So also food must be obtainable by the organisms, however small. 

 But experience alone is the perfect teacher in this matter. 



The same general method is to be followed in the collection of 

 such marine forms of vegetable and animal life as inhabit the 

 neighbourhood of the shore, and can be reached by the pond-stick. 

 But there are many which need to be brought up from the bottom 

 by means of the dredge, and many others which swim freely 

 through the waters of the ocean, and are only to be captured by the 

 tow-net. As the former is part of the ordinary equipment of every 

 marine naturalist, whether he concern himself with the microscope 

 or not, the mode of using it need not be here described ; but the 

 use of the latter for the purposes of the microscopist requires 

 special management. The net should be of fine muslin, firmly sewn 

 to a ring of strong wire about ten or twelve inches in diameter. 

 This may be either fastened by a pair of strings to the stern, of a 

 boat, so as to tow behind it, or it may be fixed to a stick so held in 

 the hand as to project from the side of the boat. In either case the 

 net should be taken in from time to time, and held up to allow the 



1 ' On some Methods of Collecting and Keeping Pond Life for the Microscope,' 

 from the Trans. Middlesex Nat. Hist. Soc. 



