No. 464.] STUDIES ON PLANT CELL.— VII. 561 
of chromosome reduction during the formation of the embryo- 
sac seems to offer an explanation of other examples of apogamy 
presented by the embryo-sac. Thus apogamous developments 
of embryos from synergids as in Alchemilla sericata (Murbeck, 
:02) or from antipodals as in 4/um odorum wil not seem 
strange if reduction processes are suppressed in the production 
of an embryo-sac and its nuclei retain the sporophyte number of 
chromosomes. Such nuclei have in them the same potentialities 
of development as do those of the nucellus whose cells form 
embryos vegetatively and entirely independent of gametophytic 
activities in a number of forms (e. g., Funkia, Calebogyne, 
Citrus, Opuntia, Alchemilla pastoralis, etc.). This type of 
apogamy from a gametophyte which retains the sporophyte 
number of chromosomes may be found to hold a very close 
relation to apospory for there is the same reduction or omission 
of the processes of sporogenesis as is found in that phenome- 
non. However, since we know nothing of the cytological events 
of apospory it is unwise at present to follow the speculation 
further. 
The peculiarities of parthenogenesis in the spermatophytes do 
not seem so remarkable since the discoveries recorded above. It 
is not strange that an egg should form an embryo without fer- 
tilization when: its nucleus contains the sporophyte number of 
chromosomes. The most remarkable feature in this suppression 
of reduction phenomena in Antennaria, Thalictrum, and Alche- 
milla is the- possibility of developing an embryo-sac with nuclei 
in the number and arrangement typical of the female gameto- 
phyte and yet with the sporophyte count of chromosomes. The 
embryo-sacs with their contents have clearly the morphology of 
female gametophytes and must be so considered in spite of the 
fact that their nuclei contain twice as many chromosomes as 
usual. It is clear that the potentialities of sporophyte and 
gametophyte involve other factors besides those of the chromo- 
some count. This isa very important conclusion because we 
have been accustomed to lay great weight on the number of 
chromosomes as the cause of sporophytic and gametophytic 
developments respectively. We must recognize the presence of 
other factors determining alternation of generations besides the 
chromosomes. 
