212 PROGRESS OF MICROSCOPICAL SCIENCE. 
irregular or stellate granule, becomes equally parietal, and appears to 
be equivalent to a nucleus, for it immediately doubles itself, and 
displays between its two moieties a partition of protoplasm, by means 
of which the spore, which has become ellipsoid, is divided along its 
smaller axis, into two equal parts. But this nucleus is so small that 
we are unable to observe the details of its division. In the partition 
of protoplasm, there is formed at the same time a new wall of cellu- 
lose, which speedily acquires a great thickness. The two small nuclei 
which generally are at first fixed near the new wall, cannot be dis- 
tinguished from the other granular contents of the spores, until these 
acquire a greater age. Finally, the membranes of the spores which 
have become bicellular, rapidly acquire a colour, which becomes 
deeper and deeper, from grey to brown. The small quantity of pro- 
toplasm which surrounds the spores becomes tinted always, by iodine, 
of a yellow-brown. 
The Blood-globules of different Races of Man.—Dr. J. G. Richardson, 
of Philadelphia, has sent us an important paper which he has published 
on this subject in the ‘American Journal of Medical Sciences.’ He 
determined to obtain from the several individuals of different parts 
of the world who went to the American Exhibition last autumn, 
specimens of their blood. And he thus describes the results :—“ The 
samples were each procured by myself from the individuals mentioned 
(sometimes only through much persuasion), by puncturing a finger 
with the quick stab of a cataract needle, pressing out a small amount 
of blood, applying a clean slide to the apex of the drop, and then 
spreading out the portion of fluid which adhered to the glass, with the 
end of another slide, according to Professor Christopher Johnson’s ex- 
cellent method. The measurements were all made with a ,';th immer- 
sion objective and by the aid of a cobweb micrometer eye-piece, giving 
when thus combined a power of 1800 diameters. The value of the 
degrees of the eye-piece micrometer with this objective, at the cover 
correction employed, was determined by a stage micrometer kindly com- 
pared for me by my friend Col. J. J. Woodward, of Washington, D.C., 
with one carefully tested by the standard in the U.S. Coast Survey 
Office, and which he has pronounced practically correct. Instead of 
measuring all corpuscles, deformed or otherwise, in two directions, as 
proposed by Dr. Woodward,* I prefer to determine the size of un- 
altered, i.e. circular corpuscles only. By this plan, which I believe 
is that of our highest authority upon the subject, Professor Gulliver, 
we obtain the dimensions of nearly normal cell elements, such as are 
exhibited in Dr. Woodward’s beautiful photograph of fresh blood,} 
where, as in fluid preparations, but little variation in size exists among 
the corpuscles; and escape being misled by pathological specimens 
similar to those displayed in photograph No. 836, of the same in- 
valuable series. Since the chief cause of marked variation in magni- 
tude as well as of distortion in shape among blood-disks spread out 
upon glass is, I think, their mutual attraction and repulsion during 
* ¢ Phila. Med. Times,’ vol. vi. p. 457. 
+ ‘Army Med. Museum,’ No. 861, New Series. 
