2/2 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



Mutterzelle." Tschistiakoff (76) says of Epilobium that the 

 division is by constriction of the plasma membrane, the cell-wall 

 being formed from the periphery inward and from the center out- 

 ward; that is, a combination of centripetal and centrifugal wall- 

 formation (p. 82)'. 



No careful and complete study of the sequence of stages has been 

 given for any one of these plants. In most instances the evidence 

 consists of an isolated drawing without a description, or a state- 

 ment with neither description nor drawing to substantiate it. 

 Lilium has perhaps been studied more than any other form. In 

 addition to Strasburger's early work, Farmer (165) in 1895 affirmed 

 that a cell-plate was present after the heterotypic karyokinesis, 

 as did Mottier (44a) a year later. Allen (la) in 1905 published a 

 figure of a cell-plate in the heterotypic division and says that the 

 same occurs in the homoeotypic mitosis. The nuclei are shown to 

 be far apart during cell-plate formation. Schaffner (61a) a year later 

 alsopubllshedasingledrawlngofacell-plate In the heterotypic divis- 

 ion. In his textbook Sachs (59) shows successive bipartition In 

 Ftmkia, "a lamella of the cell-wall completely divides the mother- 

 cell. . . . The place where the wall of the mother-cell and the parti- 

 tion-wall meet soon becomes thicker, and the two daughter-cells here 

 become rounded off." Wicgand (80) shows a figure of a cell- 

 plate after the heterotypic karyokinesis of Potamogeton, the peri- 

 pheral portion of which is without spindle fibers. Of Convallaria 

 he says, "A strong nuclear plate follows the division resulting in a 

 cross wall separating the cell into two hemispherical parts." 

 There may be some question as to whether this is the correct use 

 of the term, nuclear plate. Duggar (14Z?) gives one figure of a cell- 

 plate in the heterotypic division of Symplocarpus, and a similar 

 one of Peltandra. For Trillium Atkinson (3) gives two figures of 

 cell-plates in the heterotypic division. In like manner Schaffner 

 (616) treats Agave. For Galtonia Miss Digby (13a) shows a 

 thickened mother-wall and a cell-plate in her figure 72. In 

 figure 81 she shows the homoeotypic division occurring apparently 

 after cytokinesis had taken i)lace In the first division; ])ut in 

 figure 79 there Is no Indication that cell dI\isIon had occurred 

 previous to the second division. No discussion of this appears 

 In her paper. Tangl (70) In 1882 reported quadrlpartltlon with 

 four cell-plates accompanied !>>• an invagination of the mother- 



