ay 
im 
: 
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1910] LEWIS—PERIODICITY IN DICTYOTA 61 
At any given time all the individual plants, collected at various 
points from Capo Miseno to Santa Lucia, are at approximately the 
same stage of development. There are noticeable differences, how- 
ever, as for instance in the plants collected on April 10. According 
to the chart, this date shows the beginning of liberation of gametes, 
TABLE II 
ee % : at f develop- 
Initiation Liberation ee 
Bangor °05).) fe its ppc before the the | 3-5 tides after greatest 12-17 days 
sprin; 
Beaufort...... Day before or day of 6 days after greatest 8-9 days 
greatest spring spring 
Naples.e.045 2-3 days i least neap | 2-3 days after least neap | 16 days 
TABLE III 
HISTORY OF A SINGLE CROP 
Day Beaufort Bangor Naples 
bee mee Undivided rudiments | Undivided rudiments | Undivided rudiments 
Pe eee 8-16 cells in surface | Undivided rudiments seine rudiments 
view of antheridia or 2-4 cells 
Bare Cee ey os 32-64 cells Undivided rudiments | 2-4 ois 
Gees ai 64 cel Undivided rudiments | 2-4 cells 
Cig hoe ter General areas 2-4 cells 
Oat pe Belated s 2-4 cells 4 cells 
8.50 ae 4-8 cells 
Queer 8-16 cells 
16. Sees Many sori. 64 cells 16 cells 
EE cpu ceca 6-32 cells 
HERS CEs ee General — 32-64 cells 
13 oa Belated so cells 
1 Be pe ee elas. General abeleaes 
£6 es Belated so 
and also the beginning of initiation of rudiments. As a matter of 
fact, the numerous individuals examined on this day showed con- 
siderable differences among themselves. The male plants may be 
grouped in the following categories: (x) no antheridia empty, new 
crop not visible; (2) none empty, new crop inconspicuous; (3) very 
few antheridia empty, new crop conspicuous; (4) antheridia empty 
near base of plant, not empty near apex, new crop barely visible; (5) 
antheridia as in no. 4, new crop conspicuous, some of the rudiments 
4-celled in surface view; (6) antheridia nearly all empty, new crop 
