ey, Oe 
1900] THE CELL PLATE IN HIGHER PLANTS 83 
thus brought out from the point of view of the physiology of cell 
reproduction. 
MATERIAL. 
My observations were made largely upon (1) vegetative cells 
found in the growing root tips of various phanerogamic plants, 
among which may be mentioned Alum Cepa, Lilium longiflorum, 
Fritillaria imperialis, Fyacinthus orientalis, Vicia Faba, Phaseolus vul- 
garis, Pisum sativum; and (2) pollen mother cells of Lavix Ameri- 
cana and Larix Europea, and dividing pollen grains of Js 
versicolor and Hemerocallis fulva. 
In the first group I found the liliaceous plants were much 
more favorable for observation, and of these, owing to the ease 
with which the material could be obtained, Adium Cepa was the 
one generally used. I have satisfied myself, however, that the 
phenomena I shall describe occur in all of the plants men- 
tioned, and my conclusions are of course drawn from a study of 
all of these plants. In many particulars there is a notable differ- 
ence between the phenomena that may be seen in such tissues as 
the root tip and such cells as the pollen mother cells of the larch. 
These differences | shall attempt to correlate to some extent 
With the nature of the cells. 
METHODS. 
As some of the phenomena herein recorded are at variance 
with those observed by previous investigators, I have thought it 
worth while to give a detailed account of the methods used, even 
though they are those already well known to cytologists. Vari- 
ous killing and fixing methods were employed. Flemming’s 
chrom-osmo-acetic acid (both formulas); Hermann’s platinum 
chlorid-chrom-acetic acid; Vom Rath’s platinum chlorid-picro- 
esmo-acetic acid; Keiser’s mercuric chlorid-acetic acid; 96 per 
cent. alcohol, and a mixture of mercuric chlorid, formalin, acetic 
and formic acids arranged by Professor D. C. Worcester, of the 
department of zoology of the University of Michigan, and soon 
‘© be published by him. Of these methods, the one best 
adapted to my purpose was the stronger solution of Flemming, 
