220 THE MICROSCOPE AND ITS REVELATIONS. 



ing the bottom from the collar, and screwing on its cover, the contents- 

 may be securely preserved. The Net should be a bag of fine muslin, 

 which may be simply sewn to a ring of stout wire. But it is desirable 

 for many purposes that the muslin should be made removable; and this 

 may be provided for (as suggested in the " Micrographic Dictionary," 

 Introduction, p. xxiv.) by the substitution of a wooden hoop grooved 

 on its outside, for the wire ring; the muslin being strained upon it by a 

 ring of vulcanized India-rubber, which lies in the groove, and which may 

 be readily slipped off and on, so as to allow a fresh piece of muslin to be 

 put in the place of that which has been last used. The collector should 

 also be furnished with a number of Bottles, into which he may transfer 

 the samples thus obtained, and none are so convenient as the screw- 

 topped bottles made in all sizes by the York Glass Company. It is well 

 that the bottles should be fitted into cases, to avoid the risk of breakage. 

 When Animacules are being collected, the bottles should not be above 

 two-thirds filled, so that adequate air-space may be left. Whilst engaged 

 in the search for Microscopic objects, it is desirable for the Collector to 

 possess a means of at once recognizing the forms which he may gather, 

 where this is possible, in order that he may decide whether the ' gather- 

 ing 'is or. is not worth preserving; for this purpose either a powerful 

 ' Coddington ' or ' Stanhope ' lens ( 24), a Beale's Pocket Microscope 

 ( 76), or the Travelling Microscope of Messrs. Baker or other opticians 

 ( 78), will be found most useful, according to the class of objects of 

 which the Collector is in search. The former will answer very well for 

 Zoophytes and the larger Diatomaceae; but the latter will be needed for 

 Desmidiaceae, the smaller Diatomaceae, and Animalcules. 



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

 such marine forms of Vegetable and Animal life as inhabit the neighbor- 

 hood 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 10 or 12 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 water it 

 contains to drain through it; and should then be turned inside out and 

 moved about in a bucket of water carried in the boat, so that any minute 

 organisms adhering to it may be washed off before it is again immersed. 

 It is by this simple method that Marine Animalcules, the living forms of 



Radiolaria, the smaller Medusoids (with their allies, 

 Noctiluca, the free-swimming larvae of Echinodermata, some of the 

 most curious of the Tunicata, the larvae of Mollusca, Turbellaria, and 

 Annelida, some curious adult forms of these classes, Entomostraca, and the 

 larvae of higher Crustacea, are obtained by the Naturalist; and the great 

 increase in our knowledge of these forms which has been gained within 

 recent years, is mainly due to the assiduous use which has been made of 

 it by qualified observers. It is important to bear in mind, that, for the 

 collection of all the more delicate of the organisms just named (such, for 



