No. 464] STUDIES ON PLANT CELL.— VII. 565 
embryos when the conditions permitted of fertilization. We 
shall refer to some general considerations of Lang in our sum- 
mary and conclusions on apogamy. 
The spermatophytes present some exceedingly interesting 
examples of apogamous developments of embryos from nuclei 
within the embryo-sac other than the egg, as from antipodals 
(Allium odorum, Tretjakow, '95 ; Hegelmaier, '97) or synergids 
(Alchemilla sericata, Murbeck, : 02) or nuclei in the endosperm 
(Belanophora, Treub, '98; Lotsy, '99) but in these cases the 
sporophyte number of chromosomes is apparently present 
through a suppression of the reduction phenomenon of sporo- 
genesis in the development of the embryo-sac. 
We will now consider two studies which describe nuclear 
fusions preliminary to the appearance of apogamy (Blackman, 
:04a ; Farmer, Moore, and Digby, :03). 
Blackman's (: 04a) observations on Phragmidium have cleared 
up to a great degree our understanding of the life history of the 
Uredinales. The chains of zcidiospores have been found to 
arise serially from “fertile cells” which form a group at the 
spot where an zcidium is to be developed. Each fertile cell 
has above it a sterile cell which, however, breaks down. The 
sterile and the “fertile cell" together may represent a female 
sexual organ, the sterile cell perhaps standing for the remains of 
a receptive structure similar to a trichogyne. The spermogonium 
consists of a large mass of antheridial filaments that abjoint 
sperms which are no longer functional. It is of course uncer- 
tain whether the * fertile cells” are morphologically the original 
female gametes since they may readily be other cells drawn into 
the process of apogamy. The “fertile cell" is stimulated to 
activity by the entrance of a second nucleus either from an 
adjacent hypha or from the cell below.. The second nucleus 
does not fuse with the original nucleus in the “ fertile cell " but 
the two come to lie close together as a paired or conjugate 
The two nuclei of the pair divide simultaneously 
nucleus. ") 
ong series of nuclear divi- 
(conjugate mitosis) throughout a | 
. sions, beginning with the formation of zecidiospores and through 
the vegetative history which follows up to the production of the 
teleutospores where the members of the last pairs unite to form 
