294 Trow. — Observations on the Biology and 
liquid may be easily made to part with a single drop from 
one extremity. This nucleus fuses with the egg at the 
moment of its liberation. The egg then rounds itself off, 
pushing out the thin-walled portion of the fertilization-tube 
to the periphery and so into the periplasm. A portion of the 
antheridial contents probably passes into the periplasm, the 
rest remains behind in the antheridium. The whole process 
probably depends upon, and can be explained in terms of, 
chemiotaxis, osmotic pressure, and surface tension. 
Figs. 2i to 27 show important stages in the maturation of 
the oospore. In each case there are two nuclei. Hundreds 
of oospores have been examined in this condition, and all 
were binucleate. If a section proved to be uninucleate, as 
sometimes happened, one could with certainty predict that 
the remaining nucleus would be found in the adjacent section. 
It is noteworthy that the cell-membrane of the young oospore 
remains very thin and delicate throughout the period repre- 
sented in these sections, which, however, is no doubt a short 
one. Nuclei in a degenerate condition may be found in the 
antheridium, as shown in Fig. 22, after the membrane of 
the spore is fully formed. The order of succession in this 
series is marked by one character only, that of the gradual 
disappearance of the periplasm. The collapsed nuclei de- 
generate rapidly. They are apt to form irregular figures, 
as shown in Figs. 22 and 23, and vanish altogether before the 
last traces of protoplasm have been dissolved. 
The significance of these observations is perfectly clear. 
The whole of the periplasm is digested and absorbed by the 
young oospore, an actual increase in size of the latter being 
noticeable during the process. The explanation I ventured 
to give of the fate of the supernumerary nuclei in Saprolegnia 
and Achlya finds confirmation here. Working with pure 
cultures proved of advantage in this case. Under such condi- 
tions there could be no question of some outside agents like 
Bacteria acting as ferments and absorbing the products. The 
plant itself was the only possible agent concerned, and if 
we consider how rapidly the result is effected, and the growth 
