34 THE AMERICAN MONTHLY (Feb 
: 
made on the Minot microtome. ‘To prepare the material 
for this purpose, small parts of the frond of which a sec- 
tion was desired were taken from the Wilson’s solution 
in which they had been left for about six hours, or from 
the formalin in which they had remained an indefinite 
time, and placed in ten per cent alcohol from which they 
were dialyzed into 95 per cent alcohol. The specimens 
remained in 95 per cent alcohol for an indefinite time, 
but never less than twenty-four hours. The parts of the 
frond were then folded in small bundles of about one- 
fourth of an inch or less square and one-eighth of an inch © 
in thickness; after which they were transferred for three 
hours to 100 per cent alcohol. From this they were 
placed in a mixture of equal parts absolute alcohol and 
bergamot oil. In this they remained two hours, as they 
did in the bergamot oil to which they were transferred. 
From the bergamot oil they were passed into 45° paraffin, 
a mixture of equal parts of 45° and 54° paraffin, and 54° 
paraffin, being during that time placed in a water-bath 
which was kept at a constant temperature of 56° C. In 
each of these they remained from two to three hours. 
After this they were imbedded in 54° paraffin and on 
cooling were ready for cutting. In most cases good re- 
sults were obtained. This method was extremely useful 
in determining the number of divisions in the antheridia, 
which in comparatively thick razor sections with pith 
was very difficult to do. Razor sections were usually 
stained with eosin, while microtome sections were stained 
with acid fuchsin or with safranin. Of the two, the lat- 
ter gave the better results. 
_ In a single case, that of P. naiadum, a double stain, 
methyl]-blue-safranin, was used with exceedingly gratify- 
ing results. The slides were passed from xylol into ab- 
solute alcohol, 95 per cent alcohol, and a saturated alco- 
holic solution of safranin. Here they remained for about 
half an hour, after which the slides were placed for five 
