844 MICROSCOPIC FORMS OF ANIMAL LIFE 



much larger numbers, however, from the sand or mud dredged up 

 from the sea-bottom, or even from that taken from between the tide- 

 marks. In a paper containing some valuable hints on this subject } 

 Mr. Legg mentions that, in walking over the Small-mouth Sand, 

 which is situated on the north side of Portland Bay, he observed 

 the sand to be distinctly marked with white ridges, many yards 

 in length, running parallel with the edge of the water ; and upon 

 examining portions of these, he found Forarninifera in considerable 

 abundance. One of the most fertile sources of supply that our own 

 coasts afford is the ooze of the oyster-beds, in which large numbers 

 of living specimens will be found ; the variety of specific forms, how- 

 ever, is usually not very great. In separating these bodies from the 

 particles of sand, mud, &c., with which they are mixed, various 

 methods may be adopted in order to shorten the tedious labour of 

 picking them out one by one under the simple microscope ; and the 

 choice to be made among these will mainly depend upon the condi- 

 tion of the Foraminifera, the^ importance (or otherwise) of obtaining 

 them alive, and the nature of the substances with which they are 

 mingled. Thus, if it be desired to obtain living specimens from the 

 oyster-ooze for the examination of their soft parts, or for preservation 

 in an aquarium, much time will be saved by stirring the mud (which 

 should be taken from the surface only of the deposit) in a jar with 

 water, and then allowing it to stand for a few moments ; for the 

 finer particles will remain diffused through the liquid, while the 

 coarser will subside ; and, as the Foraminifera (in the present case) 

 will be among the heavier, they will be found at the bottom of the 

 vessel with comparatively little extraneous matter, after this opera- 

 tion has been repeated two or three times. It would always be well 

 to examine the first deposit let fall by the water that has been 

 poured away, as this may contain the smaller and lighter forms of 

 Foraminifera. But supposing that it be only desired to obtain the 

 dead shells from a mass of sand brought up by the dredge, a very 

 different method should be adopted. The whole mass should be 

 exposed for some hours to the heat of an oven, and be turned over 

 several times, until it is found to have been thoroughly dried 

 throughout ; and then, after being allowed to cool, it should be 

 stirred in a large vessel of water. The chambers of their shells 

 being now occupied by air alone (for the bodies of such as were 

 alive will have shrunk up almost to nothing), the Foraminifera will 

 be the lightest portion of the mass ; and they will be found floating 

 on the water, while the particles of sand &c. subside. Another 

 method, devised by Mr. Legg, consists in taking advantage of the 

 relative sizes of different kinds of Foraminifera and of the substances 

 that accompany them. This, which is especially applicable to the sand 

 and rubbish obtainable from sponges (which may be got in large quan- 

 tity from the sponge -merchants), consists in sifting the whole aggre- 

 gate through successive sieves of wire-gauze, commencing with one 

 of ten wires to the inch, which will separate large extraneous particles, 

 and proceeding to those of twenty, forty, seventy, and a hundred 

 wires to the inch, each (especially that of seventy) retaining a much 

 1 Trans, of Microsc. Soc. ser. ii. vol. ii. 1854, p. 19. 



