June, 1922] 
FARR MEIOTIC CYTOKINESIS OF NELUMBO 
297 
of tetrad formation, namely: the dicotyledonous type, the monocotyle- 
donous type, and the rhodophyceous type. The last-named is obviously 
the quadripartition by furrowing, the monocotyledonous type is that of 
successive bipartition by cell plates, and the dicotyledonous type is appar- 
ently held to be quadripartition by cell plates, though he gives no forms 
in which such a process occurs nor does he refer to any papers presenting 
this type of division. 
Gates and Rees (10) have just published their complete study of Lac- 
tuca in which they find quadripartition by furrowing, which they describe 
as exactly like that which I found in Nicotiana. They give five excellent 
figures of the stages of cytokinesis of the pollen mother cells. 
Several Swedish investigators have been extending very rapidly our 
knowledge of the occurrence of quadripartition and successive bipartition 
respectively in the division of the pollen mother cells of monocotyledons. 
To the work of Tackholm and Soderberg (18, 19) have been added now 
two papers, one by Soderberg (17) and another by Palm (15) just last year. 
Soderberg (17) presents a list of more than 73 species of monocotyledons 
studied by himself and others. More than 38 have quadripartition, and 
more than 34 have successive bipartition. Quadripartition, he reports, 
is found in seven families of monocotyledons and successive partition in 
four. He himself in this paper reports the first case of quadripartition in a 
palm, namely Chamaedorea corallina. Palm (15) adds to the list of Soder- 
berg observations on 8 additional families and on 19 species of families 
which have already been studied to some extent. It thus appears that 
up to the present successive bipartition and quadripartition have both 
been found in four families of monocotyledons ; quadripartition alone has been 
found in six families; and bipartition alone has been reported in eighteen 
families. In the first group are the Naiadaceae, Liliaceae, Commelinaceae, 
and Orchidaceae. In the second group are the Juncaceae, Dioscoreaceae, 
Iridaceae, Taccaceae, Cyperaceae, and Palmae. Although Palm (15) does 
not take up a careful cytological study of the details of the process, he 
mentions a few observations which are in harmony with my findings. In 
the two species of Stemona in which he found successive bipartition he men- 
tions that the mother cell walls are very thin. In Dianella, a lily, which 
has quadripartition, he reports that *'no traces of a cell plate could be 
seen during the heterotypic division"; whereas in certain of the Amaryllida- 
ceae having successive bipartition he reports that a conspicuous cell plate 
is usually present in the first division. 
In 1907 Lubimenko and Maige (13) described the cytokinesis of the 
pollen mother cells of the two water lilies, Nymphaea alba and Nuphar 
luteum. In the former they found and figured the complete formation of a 
cell plate after the first division of the nucleus, though they state that it 
may never entirely extend to the plasma membrane on all sides. This 
cell plate disappears during interkinesis. In Nuphar luteum no cell plate 
