THE DEVELOPMENT AND FUNCTION OF THE CELL 
PLATE IN HIGHER PLANTS. we 
H. G. TIMBERLAKE. 
(WITH PLATES VIII AND IX) 
(Concluded from p. 99) 
2. the genetic stage. 
THE origin of the cell plate elements occurs in the equator of 
the central spindle. In the onion this brings them in the midst 
of the carbohydrate zone (figs. 18, 19). There seems to bee. : 
doubt that they are thickenings of the spindle fibers. In the 
onion, while they are often very difficult to distinguish at first, 
owing to the fineness of the fibers and the abundance of cattt 
hydrate material, it can be determined clearly that they ae 
swellings of the fibers (fig. 29). There is nothing to sugges 
the movement of cytoplasmic granules toward the equa” — 
plane to form the cell plate in the manner described by Tresh 
Working on living cells, Treub might easily have failed or 
the beginning of the cell plate. His statement that it 
appears as a fine line would indicate this. The same © 
tion would apply to the observations of Zacharias, although ; 
to be noted that Zacharias described special bodies as ell PY 
elements and not mere undifferentiated cytoplasmic 8” 
such as those of Treub. It is to be doubted, however © vu 
these bodies have any connection with a cell plate. poe 
think it unreasonable to suppose that what Zacharias sy 
substance destined for the formation of the cell wall ™m 
shown more clearly in the larch. Here the thicket 
much more pronounced, being elongated bodies insta” * 
3 Cf. FARMER, p. 78 of this paper. 
154 
