June, 1923 ] 
YOUNG — GERM CELLS IN THE POTATO 
3 27 
segments or lobes are distinguished as nearly triangular organs having a 
central strand of vascular tissue near the inner surface. The petals, five 
in number, alternate with the segments of the calyx. They are much 
thinner and flatter than the calyx lobes and are somewhat rolled inward 
at the margins. They have central vascular strands, also two much less 
conspicuous lateral strands. The stamens alternate with the petals, and 
the anthers in section are broad, four-lobed figures, each with a central 
vascular strand. The pistil is nearly round and typically consists of three 
carpels, though pistils with two or four carpels are not uncommon. Each 
Text Fig. 2. Transverse section of bud of the Lookout Mountain potato. Note the 
horse-shoe-shaped masses of archesporial cells in the anther lobes. This section shows six 
anthers, one of which is borne on the edge of a petal. The ovary contains but two locules, 
and the beginning of ovule formation is shown by the lobed placenta. X 55. 
carpel has a central vascular strand and incloses a cavity or locule which is 
nearly filled by the placenta. Later stages are characterized by the appear¬ 
ance of additional vascular tissue, especially in the placenta, where a strand 
is produced leading to each of the developing ovules. Cells containing 
crystal sand are quite common in the carpels, placenta, and calyx. 
Development of the Pollen Grains 
The sporogenous tissue appears in the anthers at an early stage. This 
tissue consists at first of a mass of small cells with dense, deeply-staining 
