318 BOTANICAL GAZETTE [October 



was examined as in Parnassia, but enough to be sure that the 

 development of the other megaspores, if it takes place at all, is not 

 common. The position of the megaspores in the nucellus is shown 

 in fig. 79. Their great depth in the nucellar tissue is in striking 

 contrast to Parnassia, where they are immediately below the 

 epidermis, which is disorganizing at this stage. 



em 



There are no air spaces, the whole ovule being very compact and 



much more 



The 



of a mature sac is shown in fig. 81. The synergids have a well 



filiform 



as that in Parnassia. A diagram of this entire sac is shown in fig. 

 82. Two of the antipodals had disappeared. The polars have 



of the sac. 



endosperm 



Saxif 



in the examples I studied. Juel (14) shows it near the middle or 

 toward the antipodal region in S. granulata at fertilization. Fig. 

 83 is a young embryo which has just been differentiated into long 

 suspensor and embryo proper. Two endosperm nuclei are shown. 



Heuchera brixoides 



ifi 



will 



mo 



Heuchera 



mo 



(fig. 84) is shown, a 



with a laree amount of parietal tissue, and a 



mature embryo sac (fig. 86). The placentae of Heuchera 



Saxift 



Drosera rotundifolia 



This material was collected near Bonn. Rosenberg (19) ^ as 

 worked out a very interesting chromosome relationship of D. 

 rotundifolia, D. longifolia, and D. intermedia. In his early paper 

 (18) he does not figure certain stages which I need for comparison, 

 only quoting from C. A. Peters (17, p. 275) : 



Each nucellus produces a sporogenous layer of four cells, but no tapetum. 

 Three cells of the sporogenous tissue soon disintegrate, leaving the fourth, 

 which is the mother cell of the embryo sac and which undergoes subsequent cell 

 division as is usual in angiosperms. 



