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POPULAR SCIENCE REVIEW. 
wliat none of his predecessors have attempted — he has found the white 
blood-corpuscles in the blood of a living patient, by puncturing with a 
needle for a drop of blood. Besides numerous colourless granular cells of 
0-005 — 0 012 mm. in diameter, which under healthy circumstances present 
no nuclei, there were found single homogeneous, pale-yellow cells of 
0-006 — 8 mm. in diameter, with a colourless round or spindle-shaped 
nucleus, or with numerous granules (remains of nuclei). By the addition 
of acetic acid, these latter cells lost their colour, and within their contour, 
which appeared as a fine circular line, the somewhat yellowish-tinged 
nuclei and granules stood out with a sort of fatty glitter. Dr. Neuman is 
inclined to regard the presence of these transition forms between colourless 
and coloured blood-cells, which are produced by the diseased marrow of the 
bones, as a diagnostic sign of the disease of the marrow in leucoemia, since 
in a normal state they are found only in the marrow, and there h no 
evidence that in leucoemia they occur also in other organs, provided they 
are not carried into the same. In proof of this, he asserts that he has 
found nucleated cells in .the general circulation of newly-born infants at 
term, and not alone (as has already been made known) in the pancreas, 
spleen, liver, and bony marrow. How long they remain after birth is not 
certain j they were absent in a child which died of peritonitis, sixteen days 
after birth. 
Passage of the White Blood- corpuscles through the Vessels. — Dr. Norris, 
Professor of Physiology in Queen’s College, Birmingham, presented lately a 
valuable paper on this subject to the Boyal ‘Society. It is abstracted in the 
Monthly Microscopical Journal for November. Briefly, his conclusion may 
be summed up thus : 1st. Both white and red corpuscles pass out of the 
vessels through apertures which can neither be seen before their ingress 
into or egress from the vessel wall, but only during the period of transit. 
2nd. An essential and primary step in the process is, that the corpuscles 
shall adhere, or, more properly, cohere to the wall of the vessel. 3rd. 
These cohering corpuscles shall subsequently be subjected to pressure from 
within. 
The Epithelium of the Cornea and its Regeneration . — The Lancet , which 
has of late years adopted the excellent custom of occasionally translating 
good papers from foreign journals devoted to histology, recently gave an 
account of a paper in Virchow’s Archie, by J. Arnold, and an opposition 
paper by Dr. H. Heiberg, of Copenhagen, on the above subject. Arnold’s 
conclusion is that the new cells which replaced the old, when these had 
been detached, were derived from a finely-granular blastema that changes 
into protoplasm, and that in this protoplasm the new cells arise by a process 
of free cell-formation. The correctness of this conclusion is contested by 
Dr. Heiberg, who maintains the view that young cells are developed from 
the old, in which certain changes have taken place. His mode of pro- 
cedure was to scratch the surface of the cornea with a cataract needle in 
animals (frogs, birds, rats), and, after the lapse of from eighteen to forty 
hours, to remove the eye and examine the cornea both by means of fresh 
sections and after careful preparation in solutions of .chloride of gold 
(maceration for from three to five minutes in a one-half per cent, solution of 
the salt). In certain preliminary experiments it was found that the injured 
