RUBIA TINCTORIA 43 
in Callipeltis. It is to be observed, however, that the longitudinal 
divisions which are generally confined to the last four cells of the 
young embryo here take place also in a half dozen or more of the 
cells of the suspensor nearest the embryo (pl. 8, figs. 4 and 5). 
Rubia tinctoria 
(PLATE 9, FIGURES 1-6) 
The nucelli of Rubia are recognizable by their form which in 
the young condition, before the integument has commenced to 
grow, is characterized by a sharp bend on the inner side of the 
funicle. The megaspore mother-cells are fewer in number and 
are of different proportions, being shorter and thicker than the 
same structures in the rest of the Ga/zeae studied. Their nuclei 
are relatively larger (fig. 7). The tapetal cells fail here as 
elsewhere, and the division of the spore mother-cells is reg- 
ular (fig. 2) giving rise to four equivalent spores. It is a com- 
mon occurrence for several of the megaspores to divide with the 
result that a confusion is caused. The migration of the proper 
embryo-sac cell along the micropylar canal is accompanied by the 
usual divisions and the ultimate formation of an embryo-sac ( fig. 
5). The haustorial antipodal cell is broader and shorter than 
those of the foregoing forms. The other antipodal cells may be 
very small, and placed laterally or in some cases are quite large. 
In the former case they are filled with cytoplasm, in the latter case 
they have a cytoplasmic lining and the interior is filled by a large 
vacuole, : 
It is interesting to note that the embryo-sac nuclei do not cause 
the disintegration of the endodermis so rapidly as in other Gazae, 
and appear to force their way along the micropylar canal, without 
the immediate collapse of the impinging cells (jig. 3). 
In many respects the features of the archesporium and of the 
embryo-sac present the same peculiarities as have already been 
described in Asperula. There is the same tendency towards the 
formation of supernumerary embryo-sacs, and the same characters 
are shown by the persisting megaspores (fig. 4), the nuclei of 
which are supplied with a scanty amount of cytoplasm, and are 
found lying freely in the irregular cavities left by the megaspore 
mother-cells. 
