392 NOTES AND MEMORANDA. 
face and a little below it the tow-net yields certain species ; 
when sunk to greater depths, additional species are constantly 
found, and, in the deposits at the bottom, new forms occur, 
which are met with neither at the surface nor at intermediate 
depths. It would seem also that the species increase in 
number, and that the individuals are of larger size as the 
depth becomes greater; but many more observations are 
required before this can be stated with certainty. Now, if 
the belt of Foraminifera which, by their decomposition, 
according to our view, yield the ‘ red clay,’ be restricted and 
constant in thickness, and if the Radiolaria live from the 
surface to the bottom, it is clear that, if the depth be enor- 
mously increased, the accumulation of the Radiolarian tests 
must gain upon that of the ‘ red clay,’ and finally swamp and 
mask it.” 
Professor Wyville Thomson further informs me that the 
best efforts of the ‘ Challenger’s”’ staff have failed to discover 
Bathybius in a fresh state, and that it is seriously suspected 
that the thing to which I gave that name is little more than 
sulphate of lime, precipitated in a flocculent state from the 
sea-water by the strong alcohol in which the specimens of 
the deep-sea soundings which I examined were preserved. 
“The strange thing is, that this inorganic precipitate is 
scarcely to be distinguished from precipitated albumen, and 
it resembles, perhaps even more closely, the proligerous 
pellicle on the surface of a putrescent infusion (except in the 
absence of all moving particles), colouring irregularly but 
very fully with carmine, running into patches with defined 
edges, and in every way comporting itself like an organic 
thing.” 
Professor Thomson speaks very guardedly, and does not 
consider the fate of Bathybius to be as yet absolutely decided. 
But since I am mainly responsible for the mistake, if it be 
one, of introducing this singular substance into the list of 
living things, I think I shall err on the right side in attach- 
ing even greater weight than he does to the view which he 
suggests.—T. H. Huxitry.—( Nature, Aug. 19th, 1875.) 
A Method for the Microscopic Examination of Sea Water.— 
By maintaining a uniform high rate of speed, steam navi- 
gation has greatly reduced the opportunities for working the 
towing net, and many of those who want to study surface 
zoology are compelled to resort to other contrivances. I have 
found the following plan so efficient that perhaps others may 
have an interest in its description. 
It is, of course, if practicable, desirable to examine the 
