Pe enya ge 
I a a ai a a a eal el ea re a th i a 
’ 
: 
i 
1398] THE LIFE-HISTORY OF RANUNCULUS 85 
the processes of fertilization is also evident. After the apical 
cell has divided longitudinally, similar divisions may occur in 
all other cells of the primary row or in some of them (figs. 77— 
72). This variation in the formation of longitudinal divisions 
in the suspensor region is apparent even in much older embryos. 
Occasionally a late transverse division in the basal cell was 
observed (fig. 73). 
The most advanced stages of the embryo studied show con- 
siderable development of the suspensor, and the complete cut- 
ting off of a peripheral region of the embryo by periclinal walls, 
but no differentiation of the organs of the embryo. 
The students who contributed preparations and drawings to 
this paper are O. W. Caldwell, T. C. Frye, Florence M. Lyon, 
W. D. Merrell, Mabel L. Merriman, J. H. Schaffner, and W. R. 
Smith. Their initials in connection with the drawings -indicate 
the individual contributions. The laboratory work and the 
preparation of the plates were cared for by Dr. C. J. Chamber- 
ain, 
THE UNIVERSITY oF CHICAGO. 
EXPLANATION OF PLATES IV-VII. 
ae The drawings have been reduced to three-eighths of their original size, 
a with an Abbé camera. Unless otherwise indicated the ocular 
‘nation was Reichert ocular 4 and Bausch and Lomb ; oil immersicn 
PLATE AV; 
A y Microsporangium of R. seftentrionalis, showing row of hypo- 
divi ‘* archesporial cells, in one of which is a spindle of the first periclinal 
IVision, 
F : : 
cells Se e Microsporangium of R. multifidus, in which the sporogenous 
the 'stinct, and the tapetal layer appears to have been developed from 
wall. Leitz oc, 4, obj. 7a. ; 
Fig, : 
bination, ae Same, with anther wall further developed. Same com- 
Fig, : : 
tapetal — Microsporangium of R. septentrionailis, in which the prominent 
yer seems to be more related to the sporogenous cells. 
