256 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



similar in their procedure in cell-plate formation; he notes, how- 

 ever, a number of differences which evidently seemed to him of 

 minor importance, but in the light of the following discussion ap- 

 pear to be by no means insignificant. His drawings and photo- 

 graphs present the only adequate attempt since Strasburger's 

 "Zellbildung und Zelltheilung" to arrange a sequence of stages in 

 the formation of the cell-plate. The figures of cell-plates by others 

 are mostly isolated and introduced merely incidentally. 



In the onion root- tip Timberlake describes the process in less 

 detail than in Larix. He believes that new connecting fibers are 

 formed at the periphery of the spindle, both in the early stages of 

 spindle enlargement and during cell-plate formation. Except for 

 the violet-stained fibers the cytoplasm is homogeneous and with- 

 out granules. The first indication of equatorial differentiation 

 is in the appearance of an orange-staining zone in that region. 

 With the triple stain this zone stains like the young cell-wall, 

 but it does not take ruthenium red or iron-haematoxylin, so that 

 it is probably of different constitution, though Timberlake be- 

 lieves it is of carbohydrate nature. • He likens it to the orange 

 zone in Saprolegnia, and the neutral zone in Fucus. The spindle 

 fibers become apparently thinner in this orange zone, prior to the 

 appearance of the cell-plate elements, which the writer describes 

 as "thickenings of the spindle-fibers" or "swelling on the fiber." 

 He is unable to find evidence of any movement of cytoplasmic 

 granules toward the equator to form the cell-plate, as suggested 

 by Treub. The cell-plate elements are found sometimes to 

 appear before re-organization of the daughter nuclei. 



In the larch the central spindle-fibers are found not to multiply 

 by longitudinal division in the early stages of spindle enlarge- 

 ment, as Strasburger holds. But their apparent increase in 

 number is due to their separation, after being aggregated in 

 bundles by pressure of the chromosomes as they move to the poles. 

 The equatorial thickenings on the fibers are much more pro- 

 nounced than in the onion root-tip. In addition to them there 

 are granules which arc blue with Flemming's triple stain, and are 

 variously distributed within the cell during the anaphases and 

 telophases, sometimes "in rows and sometimes sticking to the 

 connecting fibers." The central spindle-fibers at first thicken 

 near the nuclei, giving the same appearance as the fibers of the 



