148 Davis. — Nuclear Studies on Pellia. 
come from studies upon the spore-mother-cell, pollen-mother- 
cell, and the embryo-sac. But more recently several detailed 
investigations have treated of vegetative tissue. It is not 
necessary to review this literature at this time. The dis- 
cussion of the centrosome problem is fresh in the minds of all 
interested in plant-cytology, and, besides, the subject has 
recently been treated in great fullness by Strasburger (’99). 
In spite of contradictory reports, the writer feels that there 
is sufficient accord among investigators to justify some general 
statements of certain events of mitosis. 
It appears probable for the Spermatophytes and Pterido- 
phytes that the spindles in the spore-mother-cell and its 
homologues arise from fibrillae developed in the kinoplasm 
around the nucleus. In early stages of mitosis the fibrillae 
may radiate from the nucleus, and later converge into brush- 
like groups. Or the fibrillae may surround the nucleus as 
a closely packed felt with a general parallelism of direction ; 
such that an axis may be early recognized. When the fibrillae 
are in brush-like bundles they sooner or later arrange them- 
selves to form two general groups, that come to lie on opposite 
sides of the nucleus, and determine the poles of the spindle. 
The behaviour of kinoplasm in vegetative tissue at the 
time of mitosis is more difficult to follow, but in the examples 
best known from the studies of Hof (’98) and Nemec (’99) 
the spindle-fibres are preceded by accumulations of kinoplasm 
(’97 and ’98) on Lilium , Podophyllum , and Helleborus ; Juel (’97) on Hemero- 
callis ; Ishikawa (’97) on Allium ; Sargant (’96 and ’97) on Lilium ; Calkins 
(’97) on Pteris and Adiantum ; Guignard (’97) on Nymphaea, Nuphar , Limo- 
dorum , and Magnolia ; Coulter, Chamberlain, and Schaffner (’ 97 ) on Lilium ; 
Lawson (’98) on Cobaea; W. C. Stevens (’98 a and ’985) on Scolopendrium and 
Asclepias ; Schaffner (’98) on Allium ; Fulmer (’98) on Pinus \ Cavara (’98) 
studies chiefly upon nucleoli and chromatin in a variety of forms ; Hof (’98) on 
Pteris , Aspidium , Ephedra , and Vicia ; Belajeff (’97 and ’98) on chromosome- 
reductions in several forms; Blackman (’98) on Pinus sylvestris\ Chamberlain 
(’98) on Pinus Laricio\ Nemec (’99 a and 995) on Allium and Solanum ; Atkinson 
(’99) on Arisaema and Trillium ; Duggar (’99) on Bignonia ; Wiegand- (’99) on 
Convallaria and Potamogeton ; Gregoire (’99) on Lilium and Fritillaria ; Gui- 
gnard (’99) on Naias ; Strasburger (’99) on Tradescantia , Iris, Larix, Osmunda, 
Nymphaea, Lilium , and other types; Williams (’99) on Passijlora ; Duggar (’00) on 
Symplocarpus and Peltandra\ Lawson (’00) on Gladiolus', Smith (’00) on Osmunda. 
