KOFOID: DEVELOPMENT OF LIMAX. 39 
man's Merkel; Fols modification of Flemming's chrom-osmic-acetic, 
cither alone or followed by Whitman's Merkel. By far the most satis- 
factory results were obtained by subjecting the eggs to the action of 
Fol's modification of Flemming's mixture for one minute and transfer- 
ring them at once to Orth's picro-carminate of lithium. The eggs were 
allowed to remain in the stain twelve to twenty-four hours, and were 
then decolorized with acidulated alcohol until the cytoplasm retained 
but a slight tinge of red. Rapid decolorization with ninety per cent 
alcohol plus five per cent hydrochloric acid gave very good results. 
Tho eggs when properly decolorized have cell boundaries and nuclear 
membranes sharply marked, and the chromatie elements of the nuoleus 
remain a deep red. Asters show plainly, but centrosomes are not 
stained. Eggs killed in Flemming's fluid and afterwards bleached by 
chlorine, or those killed in Merkel's fluid, are satisfactorily stained in 
Mayers HCl-carmine, These also must bo thoroughly decolorized. 
Eggs killed in corrosive sublimate were stained in alum-earmine or 
Czokor’s cochineal, but the best results after this killing agent were 
obtained by the addition of a drop of Delafeld's haematoxylin to slightly 
acidulated water in-which the eggs had been placed after hardening in 
alcohol (Conklin, '92). This is especially valuable for the demonstra- 
tion of astrocools in the early stages of cleavage. Satisfactory results 
were not obtained on whole preparations with Heidenhain's ivon-heema- 
toxylin or Henneguy’s method with permanganate of potash and safra- 
nin. The first, however, gives very good results with sections. 
The processes of killing, hardening, staining, and clearing were carried 
on in watch-glasses. Capillary glass tubing was found to be very con- 
venient for transferring individual eggs when such transfer was necessary. 
Turpentine, xylol, or cedar oil was used as a clearing agent. Eggs can 
be kept without harm for a long time in turpentine evaporated down to 
a waxy consistency, or in xylol to which soft parafine has been added. 
If the xylol is allowed to evaporate, it leaves the eggs embedded in the 
soft parafine, which can be redissolved by fresh xylol without harm even 
to these very delicate objects. 
The eggs were studied in the clearing agent nnder a cover-glass placed 
on glass rollers made of bits of capillary tubing. This allows the use of 
high-power objectives and. the orientation of the embryo in any desired 
position for a camera drawing. When permanent preparations were 
desired, they were mounted in xylol-balsam or a solution of dammar in 
cedar oil. By the addition of a drop of xylol to the margin of the cover- 
glass, the mounting medium is sufficiently softened to allow the cover- 
