and Fertilization in the Hemlock Spruce. 585 
solution on all sides. The solution was sometimes changed 
at the end of one or two hours. Into each bottle was placed 
at the time of fixing a small rectangular piece of linen paper 
bearing in pencil the current number. This paper remained 
with the material through all of the succeeding changes,appear¬ 
ing finally at the bottom of the paraffin block as a permanent 
and very convenient label. After fixing, the material was 
washed for twelve to twenty-four hours in running water, 
dehydrated in grades of alcohol, bleached with a seventy per 
cent, alcoholic solution of hydrogen peroxide, and the 
dehydration completed in commercial and absolute alcohol 
several times changed. It was then brought very gradually 
into cedar oil, and transferred with equal care into paraffin 
melting at 54 0 , in which it was imbedded. I have found it 
expedient to store material in seventy or eighty per cent, 
alcohol for a short time after bleaching, and to allow a 
number of bottles to accumulate before proceeding farther 
with the imbedding. Time and chemicals are thus saved and 
more attention is given to the details of the process. 
A Minot-Zimmermann revolving microtome was used in 
cutting the sections. In cases where the material was poor 
in stages, a number of ovules were imbedded in rectangular 
groups and sectioned together. Archegonia were thus 
examined by thousands instead of by hundreds. Sections 
were cut 6-6 yoc and 1 3*3 m in thickness. The ribbons were 
floated out on water, fixed to the slide with Mayer’s albumen 
fixative, dried thoroughly, and melted down by placing the 
slides in the paraffin bath for an hour or two. The slides 
were numbered with figures and letters according to the 
system devised by Marks. A mixture of vermilion and 
sodium silicate in a little water supplied a convenient and 
indelible medium. Preliminary to staining, the slides were 
passed through xylol, alcohol, hydrogen peroxide solution 
and water. Several staining combinations were used, the 
well-known Safranin-Gentian-Violet-Orange G. combination 
proving the best ; though Iron-Hematoxylin alone and 
combined with acid Fuchsin, and Delafield’s Hematoxylin 
