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160 BOTANICAL GAZETTE [SEPTEMBER 
which the cell plate is in the same stage of development, it will 
be noted that the peripheral portions show earlier stages, and 
that there are fibers connected with this latter portion whose sub- 
stance has not yet been used in the formation of the cell plate 
In many cells these fibers show all gradations from very short 
ones toward. the center of the cell to those reaching nearly, i 
not quite, to the daughter nuclei (fig. 30). Some of the latter, 
instead of extending from one nucleus to the other, extend 
simply from the nucleus into the cytoplasm of the opposite 
daughter cell. These facts would indicate that these peripheral 
fibers are radiating fibers which are taking part in the formation 
of the cell plate. The fact that the peripheral fibers appear! 
be more numerous and in a more compact layer in the stage 
represented by figs. 6 and 7 than in earlier stages (jig: 5) may 
be explained by the crowding produced by the growth of the . 
cell plate by the transformation of the inner fibers in the fashio® 
described above, 7. ¢., the peripheral fibers in jig. 6 would repr . 
sent all of the radiating fibers between the boundary of the ce 4 
plate in this figure and its boundary when it had reached a stag 
such as that shown in fig. 5. The appearance of shorter - 
on the inside of the peripheral bundles and longer ones of a 
outside shows that the process of cell plate formation goes 0 
gradually in these fibers from the inside outward. This is ee 
farther by the fact that the cell plate elements of the Ss 
fibers have already fused into a cell plate, while the interme 
ones are often distinct, and the outer fibers often show ne 
plate elements (fig. 30). The foregoing observations see” 
show that the increase in area of the cell plate is due to @ 
fold process consisting (1) of a continuous transforma! 
the substance of the original connecting fibers, Tes 
expansion of the portion of the plate around each fiber i 
consequent wider separation of the fibers; (2) concltt 
the above method occurs the addition of new cell plate or 
to the peripheral portions of the cell plate, and theif ee! uit 
the same fashion as those previously formed. These” 
processes go on in the radiating fibers which have ©? 
