678 The American Naturalist. [July, 
large specimens a dark blue color on the outside, and a purplish pink 
color on the interior, The nuclei and the cell walls are brought out 
clearly. I did not have good success with the methyl colors, as they 
were easily dissolved out by the alcohol. 
If specimens have not taken sufficient color, or if the alcohol has 
removed too much of the color, sections can be stained upon the slide, 
after they are cut. Any stain can be used, but none that I tried differ- 
entiated the parts sufficiently. Fuchsin will give enough color in a 
few seconds, The sections must stand in hematoxylin from two to ten 
minutes, and in alum cochineal from ten to twenty minutes, If it is 
intended to stain upon the slide, an alum fixative will be found better 
than collodion. 
I heated the slides in the gas flame to melt the paraffine, and poured 
on turpentine to wash it out. The specimens were then mounted. in 
balsam dissolved in chloroform. Air bubbles that appear when sections 
are first mounted, will disappear after the slides stand a few hours. If 
the razor or knife used for cutting is very sharp, small specimens may 
be cut 1-2500, or even 1-5000 of an inch in thickness. But larger 
specimens cannot be cut more than 1-600 to 1-1500 of an inch thick 
without crowding the tissues together, and giving them the appearance 
of being shrunken.—A. J. McCLATCHIE, Lincoln, Neb. 
ZOOLOGY. 
The Ontogeny of Limulus.—The following is preliminary to 
a more detailed account, with ample illustrations, which will be pub- 
lished soon. The work was done in the Marine Biological Laboratory 
at Woods Holl, Mass., during the summers of 1889 and 1890. In 
my views of the earlier stages, as seen from the surface, I fail to cor- 
roborate Osborn's account!in many particulars. The eggs were arti- 
ficially fertilized, and were carried through until hatching. 
(1) The segmentation nucleus is subcentral, and is surrounded by a 
thin pellicle of protoplasm. It undergoes several divisions before any 
signs of segmentation are visible from the surface. The products of 
this division migrate more rapidly toward that pole of the egg where the 
germ is subsequently to appear than to any other portion of the surface. 
Forty hours after impregnation the egg itself CM id a. ve 
this segmentation has in its general app harac 
1 Johns Hopkins University Circular, No, 43, 1885. 
