. STUDIES ON THE PLANT CELL. — VI. 
BRADLEY MOORE DAVIS. 
SECTION V. CELL ACTIVITIES AT CRITICAL PERIODS OF 
ONTOGENY IN PLANTS (Continued). 
5. APOGAMY. 
APocAMY is the suppression of the sexual act and the devel- 
opment of a succeeding generation asexually. The term was 
first proposed by De Bary in 1878, following Farlow's (74) 
discovery of the phenomenon in Pteris cretica. The succeeding 
generation may arise in one of two ways: (1) by the develop- 
ment of an unfertilized egg or gamete which is termed partheno- 
genesis, or (2) by some form of vegetative outgrowth from the 
sexual plant, a process which has been called vegetative apogamy. 
We shall not attempt to give a detailed account of apogamy in 
the plant kingdom but will confine ourselves chiefly to the con- 
sideration of a few detailed studies of recent months which have 
taken up the cell problems concerned. The cell problems nat- 
urally treat of the processes which may be substituted for the ~ 
sexual act in ontogeny and the fundamental problems of the 
behavior of the chromosomes under these conditions. 
. Parthenogenesis has been known for many years among the 
thallophytes which furnish illustrations in a variety of groups. 
In the algæ we have the well known examples of Chara crintta, 
Cutlaria, Dictyota, some species of Spirogyra and Zygnema, and 
a number of types in the lower Chlorophycez and Phæophyceæ 
whose motile gametes will germinate like zoóspores should they 
fail to conjugate with one another. The recent studies of Wil- 
liams (:04b) on Dictyota give the only observations which have 
been made on nuclear activities during the parthenogenetic 
development of eggs in any algal form and will be considered 
presently. The fungi furnish beautiful illustrations of partheno- 
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