EMBRYO DEVELOPMENT AND POLYEMBRYONY 
Sequoia 
In the proembryo of Sequoia (23) the tendency to an early wall forma- 
tion is carried a step further than in the forms previously described, for a 
wall is laid down after the first division of the egg nucleus (fig. 77). Each 
of these proembryo cells rounds off more or less, and the cells resulting from 
Figs. 78-82. Stages in the embryogeny of Sequoia sempervirens, X 250, after Lawson 
(23). 
Figs. 83-88. Later stages in the embryogeny of Sequoia, after Arnoldi (i); figure 87 
showing an apical cell. Figs. 86x, y, s, series of three sections through an eight-celled 
embryo showing apical cell, after Shaw (38). 
the next division are similarly dissociated. According to my interpretation, 
these cells shown in figures 79 and 80 are separately organized embryo 
initials, all but the lowest of which abort; at least their further development 
has not been observed. The lowest cell of figure 79 (or the lowest of figure 
80, a point not made clear in the account by Lawson) gives rise to the 
embryo shown in the succeeding figures, the suspensor cell being the first 
cell cut off from the embryo initial. This earlier wall formation, the pro- 
embryonic tissue filling the entire egg, and the suppression of cleavage 
polyembryony by the abortion of embryo initials, are some of the advanced 
embryo characters illustrated by Sequoia. 
There is probably at least a short apical cell stage in Sequoia, according 
to the figures of Shaw (38) and Arnoldi (i), shown here in figures 83-88. 
