EECEEATIVE SCIENCE. 



half-pint bottle, to be filled with, sea-water ; 

 after a good shake, the sand will, in a few 

 seconds, fall to the bottom, and the water 

 with Diatoms is to be poured off, when they 

 will settle as a sediment, which latter should 

 be put into the smaller bottles. 



Brackish water furnishes Siddul/phia 

 atirita, Melosira nummuloides, and fine 

 Pleurosigmas and Naviculas. 



The gathering from each place should be 

 put into a separate bottle, and it is well to 

 put in a slip of paper with the cork, on which, 

 with lead pencil, the locality may be noted. 

 Extreme care in washing bottles and corks, 

 previous to putting by for another occasion, 

 is essential. 



On getting home we may seem to have 

 brought back nothing but bottles of dirty 

 water ; this should be emptied into saucers, 

 putting the named slip by each, and with 

 a few hours' exposure to sxmlight the Dia- 

 toms will be found in a beautifully clean 

 condition, on the surface of the mud, and 

 may then be carefully removed for examina- 

 tion, and preservation, if thought desirable. 

 Of these we must treat on a future occa- 

 sion. 



In addition to those above-named it may 

 be well just to indicate other sources, some 

 of which are hardly accessible to dwellers in 

 large towns, except at the annual holiday 

 time. 



Such are the stomachs of shell-fish fresh 

 from the sea, oysters and scallops especially; 

 of crabs and lobsters, of haddock, cod, and 

 the different kinds of flat fish ; whence very 

 fine kinds not otherwise obtainable, habitants 

 of the deep sea, may be procured. It is es- 

 sential that the shell-fish should be fresh from 

 their oozy beds, since the ceaseless currents 

 produced by the action of the cilia (micro- 

 scopic hair- like processes) with which they are 

 furnished, rapidly wash the Diatoms away, and 

 the result of much patient search may, from 

 inattention to this circumstance, prove a 

 blank. A large infusorial animalcule, the 



Noctiluca, cause of muck of the phospho- 

 rescence of the sea, proves to be a capital 

 Diatom-gatherer. 



Deposits on the shores and at the bottom 

 of lakes, now or previously existent at such 

 spots ; of this many instances have been 

 recorded, in which complete strata have been 

 formed from the valves of Diatomacese, that 

 lived and died on the spots where their re-- 

 mains occur. 



Ehrenberg has described a remarkable 

 species {Orthosira mirahilis), as inhabiting 

 moss growing on trees. Our distinguished 

 countryman Mr. Ealfs started one day in 

 quest of this, and bringing home a quantity 

 of the mossy coatings of trees growing in 

 the neighbourhood of Penzance, Cornwall^ 

 his place of residence, found on his retiirn 

 that he had really got this Diatom in 

 abundance. An attempt has been made to 

 explain away the singular fact of a Diatom 

 inhabiting such a locality, by the hypothesis 

 that the examples found had been blown 

 there by the winds. But this seems a 

 purely gratuitous supposition, since it is per- 

 fectly well known that moss growing in 

 alpine localities, where it is moistened with 

 mists and the perpetual trickling of springs, 

 furnishes a home for some beautiful species 

 of the tribe ; the occurrence of Diatomaceae 

 in fragments of earth adhering to the roots 

 of dried plants obtained from various parts 

 of the world, shows that Diatoms do live in 

 moist earth. We have only to suppose that 

 the species in question is endowed with an 

 unusual power of retaining its vitality during 

 periods of drought, and the difficulty vanishes. 

 If our readers will take up this question, it 

 may soon be solved ; they wUl find it one of 

 exceeding interest, and furnish valuable aid 

 to the cause of science. The words used in 

 the definition, were in effect that they gene- 

 rally lived in water, but certainly not at all 

 times, invariably. 



TuFFEN West. 



