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POPULAR SCIENCE REVIEW. 
termination of some period of the existence of the species, and the intense 
green colour he conjectures to be indicative of sporidification. 
Application of Magenta Dye to Microscopical Investigations. — At a recent 
meeting of the microscopical section of the Literary and Philosophical 
Society of Manchester, Mr. Roberts called attention to the aid that might 
be received in the examination of the structure of animal and vegetable 
tissues by the use of colouring materials. Magenta is peculiarly adapted 
for this purpose, in consequence of its solubility in simple water, and its 
inert chemical character. The nuclear structures of animal cells are 
deeply tinted by magenta, and by its use the nuclei of the pale blood 
corpuscles, of pus globules, of the renal and hepatic cells, and of all 
epithelial structures are brought out in great beauty, tinted of a bright 
carbuncle red. The red blood discs are tinted of a faint rose colour, and 
a darker red speck, not hitherto noticed, is to be observed on the periphery 
of the corpuscle ; it undergoes some changes when treated with tannin, 
and subsequently with caustic potash ; but this point is still under 
investigation. 
Cleaning Diatoms.- — Mr. J. A. Tulk recommends the light detachment of 
the diatomaceous stratum on the surface of the moist or immersed mud by 
the aid of a small, old salt-spoon, by which means it is taken nearly free 
from siliceous particles. The bottle should contain a little water. If the 
mud be dryer, a camel’s-hair pencil is useful. They should then be 
strained through a piece of thin silk gauze, and placed in a saucer with 
an eighth of an inch of water above the stratum, and exposed for a few 
hours to sunlight, which in many instances causes the diatoms to ascend 
above the impurities, where they may be known by their brown colour, 
and may be separated by a camePs-hair brush. In many cases boiling in 
nitric acid, and washing in clean water, is all that is required. If not, 
successive washings in a wide-mouthed bottle gets rid of a great deal of 
minute matter, and further boiling in sulphuric acid and chlorate of 
potash, and subsequent violent shaking in clean water, gets rid of floccu- 
lent siliceous matter or mucus. When the microscope shows the super- 
natant fluid to be clear of siliceous particles, a whirling motion given to 
the diatoms in a flat-bottomed saucer, half-full of clean water, brings the 
frustules to the surface, whence they may be removed by the capillary 
dipping tube. 
The supposed Microscopic Jaw. — Mr. G. Busk, F.R.S., in the Micro- 
scopical Journal, shows reason to believe that Mr. Spence Bate’s conjecture 
as to the crustacean origin of this pseudo-morpli is not the true explana- 
tion, and gives figures of pedicellaria-valves of species of echinus, in 
juxtaposition with the jaw itself. These pedicellarise consist of three 
valves, articulated in a complex manner to each other. Each valve 
possesses a serrated margin, large denticles on the anterior ridge, a large 
denticle in front of the median ridge, and lateral condyles — all of which 
well agree with the appearances presented by the object in question. Mr. 
Busk remarks that a full account and accurate figures of the varieties 
which exist in the pedicellarise of various echinidse and asteridse, would 
afford a subject for a very useful and interesting paper, and might assist, 
perhaps, very considerably, in the discrimination of species or genera of 
