35° The Ohio Naturalist. [Vol. Ill, No. 3, 



The antipodals are absorbed very early (Fig. 8), and the sac 

 enlarges very rapidly, especially from the antipodal end, forming 

 almost a complete circle and enclosing a mass of the basal cells of 

 the nucellus in the center of the camph\lotropous ovnle 

 Fig. 22). The first division of the endosperm occurs at about the 

 same time as the first division of the embryo. After that it 

 divides very rapidh-, forming the typical peripheral endosperm^-- 

 lining the embryo-sac i Fig. 16). At the antipodal end of the sac 

 the endosperm is always more dense than in other parts of the 

 sac (Fig. 17), and probabh' makes the absorption of the nucellus 

 more rapid. The micropyle and the pollen tube (Fig. 16) were 

 very clear in many preparations, but the act of fertilization was 

 not observed. However, several cases were observed which indi- 

 cated that the second spernr nucleus might unite with the two 

 polar nuclei, but were not sufficiently clear to draw a conclusion. 



EMBRYO. 



The fertilized egg divides b}- tran.sverse walls to form three or 

 four cells in an axial row (Figs. 9-12). Typically the row con- 

 sists of three cells developed in acropetal order. The upper of 

 these cells next divides by a longitudinal wall (Fig. 10). This is 

 followed by a similar division in the next lower cell (Fig. 11). 

 The two upper cells now divide by longitudinal walls at right 

 angles to the first, thus forming a quadrant (Fig. 12). In the 

 meantime one or more transverse walls have been formed in the 

 basal cell, thus lengthening the suspensor. The embryo proper 

 is now usually composed of three or four tiers of cells (Figs. 13, 

 14, 15). Each tier of cells divides first longitudinally and then 

 more or less irregularly, by both transver.se and longitudinal 

 walls, forming an embryo almost spherical in shape, but slightly 

 larger on the side away from the funiculus ( Figs. 13, 14, 15, 16, 

 18). The protoplasm in the upper two-thirds of the embryo is 

 usually more dense than in the lower one-third (Fig. 16). 



The suspensor originates as a single cell (Figs. 9-12). This 

 cell usually divides b}- the formation of transverse walls (Figs. 

 13, 14, 16), but occasionally divides by longitudinal walls (Fig. 

 15). The formation of transverse walls is followed by a longi- 

 tudinal division in either one or both cells (Figs. 16, 18). After 

 this it was impossible to follow the divisions. However, it 

 always remains short, but becomes verj- much widened (Fig. 19) 

 as a result of longitudinal division. By the time the embryo has 

 reached three-fourths full .size the suspensor has usually disap- 

 peared ( Fig. 20). 



The cotyledons originate from opposite points of the almost 

 spherical embryo (Fig. 18, c, c). The outer of these two points 



'■' Hegelmaier, Dr. Untersvichungen ueber die Morphologic der Dicotyledonen-Endo- 

 spernis. Nova Acta d. K. L. C. D. Akad. d. Naturforcher /)9. 1885. 



