530 
SUMMARY OF CURRENT RESEAT CHES RELATING TO 
Carmine is the best stain for fishes’ teeth. If it is used, however, it is 
necessary before transferring to distilled water to pass the section 
quickly through weak HC 2 H 3 0 2 as this “ fixes ” the stain. If gold 
chloride is used the specimens must be mounted in glycerin-jelly. . . . 
(5) It is unnecessary to cut sections of enamel to demonstrate the 
prisms. After having softened enamel by immersion in 10 per cent, 
solution of II Cl, remove by means of a needle-point or fine brush a small 
portion to a slide ; put a drop of normal salt solution on to the top of 
the enamel, and press down cover-glass. Then run a solution of car- 
mine or orange-rubine beneath the cover-glass, and draw off the excess 
with a little blotting-paper. Wash the stain away further by irrigation 
with weak HC1, or HC 2 H 3 0 2 , and mount in this solution or acidified 
glycerin after Beale’s plan. 
Examining Nuclei of White Blood - corpuscles.* — The ordinary 
notion about white corpuscles, viz. that the majority are polynucleated, 
is, says M. Mayet, quite erroneous. By this the author does not mean 
that polynucleated corpuscles are not demonstrable, but that this con- 
dition is extremely rare. 
To ascertain exactly the shape of the nucleus, glacial acetic acid 
must be intimately mixed with the blood in the proportion of three 
to one. 
By this means the red corpuscles are rendered almost invisible, 
while the extra-nuclear part of the white is more or less dissolved, so that 
the nuclei are isolated and become very visible. 
The nucleus then is found to be of very variable shape, and it is 
owing to this irregularity that various optical effects are produced, so as 
to give the appearance of more than one nucleus. The nucleoli are 
always multiple, there being one for each swelling of the nucleus. 
When a white corpuscle is really polynucleated, it is just in the act 
of division, nucleus and extra-nuclear plasma as well, but this condition 
is rare. 
Studies in Cell-division.f — Prof. D. H. Campbell recommends the 
following subjects as specially well adapted for showing the various 
stages of division in the plant-cell, and its modifications ; the paper is 
accompanied by very good figures : — For cell-division where there is 
no definite nucleus — Nostoc. For division of a multinucleate cell, and 
division of the nucleus independently of cell-division — Cladophora. For 
cell-division accompanied by the division of the single nucleus — Spiro- 
gyra. If exposed to cold during tbe night, and brought into the 
laboratory in the morning, some of the cells will probably begin to 
divide almost immediately. An interesting modification of the process 
is shown by many desmids. For following the process in the living 
cell — the hairs on the filaments of Tradescantia virginica. It is well 
shown by removing the stamens from the young buds, and mounting the 
attached hairs in water or in a 3 per cent, solution of sugar. They 
may be stained without killing them by a weak aqueous solution of 
methyl- violet, dahlia, or mauvein. For easy demonstration of the 
process of karyokinesis — the final divisions of the pollen-mother-cells, 
* Comptes Rendus, cx. (1890) pp. 475-7. 
f Bull. Torrey Bot. Club, xvii. (1890) pp. 113-21 (2 pis.). 
