ee 
Toor] GAMETOGENESIS AND FERTILIZATION 1N ALBUGO 249 
having no oosphere, and into which an abundance of nuclei are 
poured. From these conditions, as well as direct observation, 
it is clear that the number of males and females is not exactly 
equal. In A. 7ragopogonis unpaired male pronuclei are some- 
times seen in the fertilized oosphere, but they are eventually 
digested by the ooplasm. Similarly, those male nuclei which 
do not pass into the antheridial tube, and those lying in an 
antheridium which forms no tube, fail to resume vegetative 
function and may be found im situ in stages of degeneration. 
The inability of such nuclei to function vegetatively attests 
their sexual differentiation and accounts for their subsequent 
rapid elimination. 
One observation may help to disclose the force which directs 
the antheridial tube in its penetration of the oosphere. Two 
abnormal oospheres were seen quite devoid of nuclei. In one of 
these only the plasmoderma was developed (fig. 52), in the 
other periplasm and ooplasm were separated by a wall. In both 
cases the only antheridial tube present had gone astray in the 
periplasm. The absence of oospheric nuclei and the misdirec- 
tion of the tube in the same oosphere may be only a peculiar 
coincidence. 
Immediately after the opening of the antheridial tube a wall 
is seen surrounding the oospore. This develops with great 
rapidity, often attaining considerable thickness before the pro- 
nuclei have begun to fuse. Later thick walls, composed princi- 
pally of cellulose for the nourishment of the germinating spore, 
are laid down from the inside, and on the outside heavy brown 
walls which are characteristically corrugated.’ 
In teratological forms, which abound in all species of Albugo, 
antheridial tubes where they lie in contact with the periplasm 
are frequently seen coated with the characteristic pectiniferous 
deposit. This occurrence was noted by DeBary (1863), and 
7 For brevity I shall hereafter use the term _esemteoats to hein sueme this charac 
teristic brown coating, inasmuch as pectin seems to b t which is ee 
ere and absent from the other parts of ie fungus. From the literature at hand the 
deposit appears to be really a mixture of cellulose, callose, cutin, and pectin, although 
its actual composition is yet open to question (Magnin 1895, Zalewski 1883). 
