CELL DIVISION BY FURROWING IN MAGNOLIA 
but later they are seen to be composed of fibers that run from each of 
the two sister nuclei on the one side to each of the two sister nuclei on 
the other. So that there are fibers running between every pair of 
nuclei in the tetranucleate cell, just as in the tetrahedral pollen mother 
cells of Nicotiana (6). In the latter case there are thus six distinct 
spindles, but in Magnolia there is some question as to whether they 
should be considered as six separate spindles or as two simple spindles 
and one compound spindle (figs. 14 and 24). 
The formation of the spindle fibers in the heterotypic equator after 
the homoeotypic karyokinesis presents a problem which has as yet 
never been satisfactorily solved. Most central spindles are organized 
as a consequence of mitotic karyokinesis, just as occurs in the formation 
of the primary heterotypic and homoeotypic spindles in these cells. 
But in multinucleate cells that are formed by successive mitotic 
division of a primary nucleus, one or more spindles are apparently 
organized in some other way. In Nicotiana and several other Dicoty- 
ledons (6) four spindles are thus formed ; in Magnolia there is one com- 
pound spindle so organized. In the last-named form this compound 
spindle lies in exactly the same place as did the primary heterotypic 
spindle, although the fibers in the two spindles are not arranged in the 
same way. The primary heterotypic spindle completely disappears 
as the homoeotypic division begins, and no semblance of it is found 
until after the new nuclei are formed. In the telophase a large number 
of fibers again appear. Whether these represent a reorganization of 
the primary heterotypic spindle, or the formation de novo of a large 
number of fibers is not entirely clear. The cells in the metaphase 
and anaphases show no spindle fibers (fig. 9) across this area. The 
cytoplasm in the equatorial region is granular, or in some cases ap- 
parently alveolar, and stains blue with the Flemming's treatment. 
The area of this type comprises about one third of the space between 
the two nuclei while the other two thirds between it and the two nuclei 
respectively is of a different composition. This latter takes on the 
orange stain and is homogeneous in appearance rather than granular. 
This orange area is widest on the equatorial side but extends around 
toward the opposite side for varying distances until it gradually disap- 
pears. No indications of fibers are to be found in this orange area, but 
it is not unlikely that it may be composed of material which once made 
up the fibers of the primary heterotypic spindle and which will again 
form the secondary one. In figures 24 and 25 of the writer's paper on 
