250 THE MICROSCOPE. 



species of Schizonema; and it consists of a quantity of 

 gelatinous hollow filaments filled with an immense number 

 of bright-brown shuttle-shaped bodies, like very minute 

 naviculce. 



" It is not necessary to be particular about collecting 

 the specimen free from mud, as the filaments are so tough 

 that the mud can be readily washed away by shaking the 

 whole violently in a bottle of water, and pouring off the 

 mud, without at all injuring the specimen. The Amphi- 

 porium alatum communicates a somewhat frothy appear- 

 ance to the otherwise clear water, and to get any quantity 

 of this requires a little management ; but by skimming 

 the surface with the spoon, and using one of the larger 

 bottles, an abundance may readily be obtained. Between 

 the sea-wall and the river the marsh is intersected in every 

 direction with a number of meandering creeks, being in 

 some places eight to ten feet deep, though in others quite 

 shallow; but it is exceedingly difficult to make one's way 

 amongst them, and I have never found them so prolific 

 any where, on the few occasions of my visiting the place, 

 as in the parts more away from the influence of the tide. 

 It will be observed, that the brilliant brown colour, of a 

 deep but bright cinnamon tint, is one of the best indica- 

 tions of the presence of diatomacece; and though this is by 

 no means universal, the variation is most frequently de- 

 pendent upon the presence of something which qualifies 

 the tint. The peculiarity of the colour is due to the 

 endochrome contained in the frustule; and this must in 

 general be got rid of before the beautiful and delicate 

 marking can be made out. But it is highly advantageous 

 and instructive to view them in a living state ; and this 

 should be done as soon as possible after reaching home 

 with all specimens procured from salt-water localities, as 

 they rapidly putrefy in confinement, and emit a most 

 disgusting odour, not unlike that arising from a box of 

 inferior congreve-matches. 



" Washing in fresh water, and then immersing in creo- 

 sote water, preserves many of the species in a very natural- 

 looking manner; but they are killed by the fresh water, 

 and the endochrome becomes much condensed in the 

 Pleurosigmata and some other species. The addition of 



