64 BOTANICAL GAZETTE [january 



. In Coulter and Chamberlain's book (4) it is stated that 

 "the endosperm is said to develop only in the antipodal chamber 

 in Loranthus, Vacciniaceae, Verbenaceae, etc." This statement 

 should be corrected as far as it concerns the various species of 

 Verbena which I have studied. 



Development of embryo 



The proembryo divides in two by a transverse wall and remains 

 without further change for a long time (fig. 49). It then elongates, 





with accompanying divisions, reaching a condition like that 



illustrated in fig. 53, where it is a 

 filament of varying length, con- 

 sisting of several cells. The apical 

 cell of the filament then divides 

 longitudinally (fig. 54) , followed by 

 55 .56 '57 another longitudinal and a trans- 



Figs. 54-57.— V. hastata: succes- verse division in either order, result- 



sive stages of development of embryo; j ng [ n an oc tant stage (figs. 55, 56) . 



fig. 56, apical view of stage in fig. 55; The dermatogen pe riblem, and 



X400. o i sr f 



plerome layers are next differ- 

 entiated in the embryo (fig. 57), which now occupies the end of a 

 long suspensor. The appearance is identical with that of Capsella. 



Relationship of intermediate forms 



- 



Cook, comparing two species of Sagittaria, S. variabilis and 

 S. lancifolia, says: "With such striking external differences one 

 would naturally expect equally interesting internal differences, 

 but to my surprise I found the development of the embryo sac 

 and embryo of S. lancifolia practically the same as had been 

 described by Schaffner for S. variabilis" I was equally surprised 

 on comparing the forms of Verbena. I selected as the intermediate 

 form for comparison with the original species the type designated 

 in the earlier part of this paper as no. 5 (see fig. 5), because it is 

 one of the most abundant of the intermediates and because it 

 seemed to be halfway between V. stricta and V. hastata. In the 

 following account the morphological and cytological characters 

 of this intermediate are compared with those of the three species. 



