KING: CYTOLOGY OF ARAIOSPORA PULCHRA. 
237 
III 
I 
algae mentioned. He regards it as a zymogenic region of the proto¬ 
plasm of the oogonial cell and homologous with the papilla of dehis¬ 
cence of zoosporangia. If zoosporangia and oogonia are homol¬ 
ogous organs as Thaxter (’95a) has certainly shown by his figures 
in Monoblepharis insignis and M. fasciculata , it is clear that these 
structures must also be homologous. In any case, there can he 
no doubt as to the homology between the receptive papilla of 
Araiospora and the structure in the algae mentioned above. In 
Araiospora it is always a differentiated portion of the oosphere, it 
perforates the oogonial wall, and finally it is the part of the egg 
that receives the sperm nucleus. 
Cytologists are generally agreed that the process of fertilization 
has two functions: a rejuvenescence of the fertilized cell and the 
transmission of two more or less distinct lines of descent. If this be 
true, it is clear that the second of these purposes can be realized 
only where nuclear fusion takes place; otherwise there can be no 
blending of chromatin substances. There have been a number of 
recent experiments on the eggs of certain animals that tend to show 
the Independence of these two functions of fertilization. The well 
known experiments on the eggs of Toxopneustes indicate clearly that 
rejuvenescence can be brought about without the aid of a sperm 
nucleus, the bearer of the hereditary characters of the other line of 
descent. Furthermore, Wager (’ 99 ) suggests that m certain fungi in 
particular, the excitation to activity of the fertilized cell is the more 
important function, since in many cases, the lower plants often pro¬ 
duce the two sexual organs in close proximity to each other and 
the nuclei must of necessity represent essentially the same line 
of descent. 
In Araiospora these two functions stand out in sharp contrast. 
Until the sperm nucleus is introduced the central ooplasm is sharply 
differentiated ; immediately afterward the previously described pe¬ 
ripheral migration of the central mass occurs; this is followed by 
an accumulation of a large, central globule and the formation of a 
thick oospore wall. As these changes occur, the nuclei remain 
distinct but increase o;reatlv in size. Mention has been made of 
other instances of delayed fusion of the sexual nuclei. In Basidiob- 
olus (Fairchild, ’ 97 ), the wall of the oospore is well developed 
before the nuclei fuse, although they have been lying side by side 
for some time. In Monoblepharis (Lagerheim, :00) the sexual 
