64 BOTANICAL GAZETTE [yoLy 
(1) when transferred from foul to distilled water, (2) when brought 3 
from darkness into light, (3) when water is replaced by sugar solution. — 
KLEBs’s investigations (3) illustrate the same point for other algae q 
and fungi. Since the fructification of other forms may be induced — 
by different factors, it is possible that the same may be true for Dic- _ 
tyota in various situations, and that the factors concerned in inducing — 
periodicity may vary with the locality. 4 
Other organisms, both animals and plants, show a periodicity — § 
in the release of sexual cells comparable to that of Dictyota. In a 
Amphitrite ornata, an annelid worm, “practically all sexual products — 
are deposited within three days of spring tides” (Scott 6, p. 332). _ 
Kuckucx finds (4) in Nemoderma tingitana that the gametes are — 
released at times of neap tides. TAHARA shows (7) that the oospheres 4 
of Sargassum enerve are released at fortnightly intervals at about the 
time of new and full moon. Other species of Sargassum are said : 
by Tawra to show a similar periodicity, in which liberation occurs 
at various intervals after the greatest spring tides. a 
It is obvious, therefore, that periodicity in the release of sexual — = 
cells is a widespread phenomenon, probably to be attributed tom 
various factors in different species, and perhaps to more than one — q 
factor in the same species in different localities. 
RANDOLPH-Macon COLLEGE 
ASHLAND, VA. 
LITERATURE CITED 
I. FREUND, H., Neue Untersuchungen iiber die hiring der Aussenwelt auf 
die Gngeichlechdiche Fortpflanzung der Algen. Ta 98:41-100. 1907. 
- Hoyt, W. D., Periodicity in the ae of ‘ie sexual cells of Dictyota 
dichotoma. Ror. GAZETTE 43:383-392. 
3- Kiezs, G., Die Bedingungen der eis bei einigen Algen und 
Pilzen. tena: 1896. 
4. Kucxuck, P., Neue panies iiber Nemoderma. Wiss. Meeresunters- 
Abt. Hieléslaad N.F. 5: 190. 
5. OLTMANNS, F. "Magda und Biologie der Algen 2:59. Jena. 1905- 
6. Scorr, J. W., Some egg-laying habits of Amphitrite ornata Verrill. 
Bull. 1'7:332. 1909. 
Tanara, M., On the periodical —— of the oospheres in Sargassum 
as Bot. Mag. Tokyo 23:151-153. 
. WitrraMs, J. Lt., Studies in the Reig III. The periodicity of the 
sexual cells in Dowels dichotoma. Annals of Botany 19:531-560. 1905- 
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