84 FECUNDATION; HETEROGAMETES. 
In var. crassésepta with uninucleate egg-cells the problem is simpler. 
The observation of the process in this form in connection with var. 
drauniz was fortunate, as it must have served as a contrel in the 
interpretation of the phenomena in the multinucleate eggs. If the 
observations of Klebahn be correct, var. 6raunzd represents the only 
authentic case among the alge of a normal sexual union of a single 
male and female nucleus in an egg-cell containing several nuclei of 
apparently equal morphological value. 
FUCACE. 
In certain respects the sexual process in Spheroplea is suggestive 
of that in the Aucacee. Inthe latter, however, we have the addi- 
tional feature that the female gametes or eggs escape into the water, 
and copulation takes place outside of the odgonium. Probably no 
other representative of the alge is so favorable for the observation 
of the external phenomena of the sexual process than is Fucus. 
The more obvious details of the process have been observed by 
Thuret, Oltmanns and others, but it is to the recent researches of Far- 
mer and Williams (’96,°’98) that we are indebted for a thorough 
and comprehensive account of the phenomena to be observed in the 
living material. The work of these authors supplements also the 
observations of Strasburger (’97) on the development of the gametes 
and on the behavior of the sperm-nucleus after it enters the egg. 
The type of division of the cell and nucleus in the development of 
the gametes in this group of plants has been fully treated in the intro- 
ductory chapter, and the escape of the egg-cells from the odgonium is 
too well known to bear repetition in this place.’ Since, however, 
Fucus has figured prominently ip recent and much discussed theories 
bearing upon the significance of the number of the chromosomes in 
sex and heredity, it is probably not out of place here to state that, in 
the first nuclear division in the odgonium, the reduced number of 
chromosomes appears, and that both the nucleus of the egg and the 
spermatozoid contain this number. 
In order to observe the behavior of the sexual cells while alive, and 
to obtain suitable material for the indirect method of study, Farmer 
and Williams state: 
Male and female plants were kept in separate dishes, and were covered to 
prevent drying up. . . . On the appearance of the extruded products, the 
female receptacles were placed in sea-water, and after the complete liberation 
of the oospheres a few male branches with ripe antherozoids were first placed 
2 On the method of the liberation of the sexual cells, see Farmer and Williams, ‘98, p. 629. 
