248 BOTANICAL GAZETTE [OCTOBER 
they can occur in the entire absence of the female. It is after 
expulsion from the paternal gametangium that the chemotactic 
influence of the female unit is exerted upon the males. In the 
ferns, mosses, and most algae the chemotactic influence of the 
female extends over a comparatively wide region. In the 
spermatophytes the area is much restricted, since the pollen 
tube opens near the oosphere. In the Albuginaceae, where the 
male gametangium opens directly into the female gametangium, 
the region over which this influence may be exerted is still 
more limited. Indeed it may be questioned whether the force 
which brings the nuclei of the coenogametes (Davis 1900) 
together in pairs is at all the same as that which brings gametes 
together in the open. The pairing of nuclei in multinucleate 
masses of cytoplasm is comparable to the pairing of the male 
and female nuclei after the sperm has entered the cytoplasm of 
the egg, as is readily apparent from a consideration of the con- 
ditions presented in the larger eggs, as Fucus. Pfeffer demon- 
strated that the gametes in the open are drawn together by 
chemotactic attraction, and Wilson (1900) assumes that a simi- 
lar attraction brings the nuclei together in the cytoplasm of the 
egg. Apparently two different forces operate, one to bring the 
sperm to the egg and induce penetration, the other to bring the 
pronuclei together inthe ooplasm. Conklin (1899) has already 
distinguished these as distinct factors, and attempts to prove 
that in some cases at least cytoplasmic currents are responsible 
for the movement of the nuclei in the cytoplasm. Such an 
explanation does not seem adequate for the multinucleate 
oosphere of Albugo, as it would involve complexity inconceiva- 
bly great. An explanation resting on chemotaxis is more tenable. 
Conditions where an antheridial tube has reached the 
oosphere after that organ has been fertilized by another tube 
Jig. 48), as well as cases where two tubes open into one 
oosphere (fig. 51), show there is no correlation between the 
number of female nuclei to be fertilized and the number of 
nuclei which pass from the antheridial tube. This is also 
emphasized in fig. 50, where a tube is opening into an oogonium 
