Notes . 
483 
with it. Judging from the short period of time elapsing between its 
penetration of the surface of the oosphere and its arrival at the 
exterior of the female nucleus, it must pass through the intervening 
cytoplasm with great rapidity. It then becomes closely appressed 
to the nucleus, and is about as large as the nucleolus of the latter. 
It rapidly spreads over a part of the female nucleus as a cap, and it 
presents a less homogeneous aspect than before. Both it and the 
female nucleus assume a granular condition, which is probably to be 
interpreted as representing a coiling and looping of the linin of the 
respective nuclei. Finally the two nuclei coalesce, and the original 
components can no longer be distinguished. Complete fusion may 
be effected in less than ten minutes after addition of the antherozoids 
to the water. The results are in striking accordance with those 
described by Wilson in connexion with the fertilisation of the eggs 
of Echinoderms in his recent Atlas of Fertilisation, 
A delicate pellicle is meanwhile formed around the periphery of 
the oosphere, which is thus easily distinguished from the unfertilised 
oospheres, in which such a membrane in wanting. The texture of the 
cytoplasm also changes, and tends to assume a more definitely radiating 
character, the lines starting from the nucleus as a centre. 
We observed, not unfrequently, rather large cells in which two 
nuclei of equal size were lying in close juxtaposition. These cells, 
with their nuclei, answer exactly to the description given by Behrens 
of the fertilisation stage in plants examined by him. We are unable 
however to accept his interpretation, for, in the first place, the series 
of fertilisation stages which we have observed, and have briefly described 
above, in no way correspond with the appearances described by him, 
and secondly, because these large cells (Behrens himself emphasises 
their size) are seen in material to which no antherozoids have had 
access. Furthermore, the average size of the young oospores is not 
obviously greater than that of the oospheres themselves. We regard 
the bodies in question as representing abnormal developments of 
oogonial cells, and not as being in any way concerned with fertilisation. 
Moreover, we have occasionally observed one cell in the divided 
oogonium much larger than the rest, to contain two, or even some- 
times three, nuclei, and these nuclei are then always close together. 
These facts have led us to reject Behrens’ account of the process. 
A very large number of experiments were made, in order to deter- 
mine, if possible, the time which elapsed between the addition of 
