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1901 | GAMETOGENESIS AND FERTILIZATION IN ALBUGO 243 
possible, therefore, that mere accident determines how many of 
the nuclei are to be so oriented as to contribute daughter nuclei 
to the oosphere. It is needless to attribute to the cytoplasm any 
special selective power which causes definite nuclei or a definite 
number of them to return, although such selection is exhibited 
in some plants. For example, in the oogonium of Vaucheria 
- (Oltmanns 1895) one nucleus maintains its position near the 
beak, amid violent activities of the surrounding cytoplasm, while 
the chloroplasts and numerous other nuclei are withdrawn. In 
the oogonium of Peronospora, according to Wager (1900), one 
nucleus of the many is selected to reenter the ooplasm and func- 
tion as the female pronucleus. 
The elimination of supernumerary nuclei by digestion in the 
surrounding cytoplasm finds analogy in vegetative cells in the 
Sieve tubes of Pinus (Strumpf 1898); and still more striking in 
the sexual cells of Achlya (Trow 1899, p. 156), where there is 
an average of ten times as many nuclei as there are eggs to be 
produced. The phenomenon is also analogous to that described 
by Riickert (1892) and Oppel (1892), where several male nuclei 
enter the egg, the superfluous ones degenerating and functioning 
as yolk nuclei. In Actinosphaeria Hertwig (1898) also describes 
a reduction from multinucleate to uninucleate condition before 
fertilization, which is essentially similar to that seen in Albugo, 
the supernumerary nuclei being dissolved in the surrounding 
cytoplasm. In this species, as in Albugo, the nuclei are all 
alike, showing no such differentiation as is common among the 
infusoria. The phenomena seen in the Fucaceae (Oltmanns 
1889), particularly in Himanthalia lorea, may be classed in this 
Same category. Here the cytoplasm in early stages contains 
eight nuclei, the number being later reduced to one by casting 
off the seven superfluous ones. 
In Vaucheria (Oltmanns 1895) the reduction from a multi- 
nucleate to a uninucleate condition is effected in quite a different 
manner, by protoplasmic streaming, the supernumerary nuclei 
being carried back into the parent hypha. Thus the reduction 
occurs before the oosphere is differentiated, and not in the 
