266 Shaw — The Fertilization of Onoclea . 
the case. In the light of this result the writer’s experience 
with Chara affords ground for questioning whether partheno- 
genesis in that genus is confined to the dioecious species, 
C. crinita. 
The spores of Onoclea sensibilis had been brought by 
Dr. Campbell from Massachusetts. They were sown in the 
laboratory, some in September, 1895, and others in January, 
1896. When the earlier culture was examined in January, 
some of the female prothallia were found to have formed 
mature archegonia, but when they were placed in water most 
of the archegonia were slow to open. Spermatozoids were 
set free in a few minutes after male prothallia were placed 
in water. On February 26 spermatozoids crowded into and 
about the open archegonia within eight minutes after the 
prothallia were placed in distilled water. In Marsilia the 
first division of the embryo takes place within an hour after 
fertilization, and in Pilularia after about three hours 1 . Dr. 
Campbell, by his extensive studies of Fern embryology, was 
led to believe that the first division of the egg of Onoclea 
occurred about twenty-four hours after fertilization. It was 
desired to obtain a series of prothallia which would represent 
as completely as possible the period intervening between 
the entrance of the spermatozoid into the archegonium and 
the first division of the egg, for it was the intention at the 
outset to describe the nuclear and cytoplasmic structures 
and changes within the egg during that period. On February 
2 6 and the two following days, prothallia were left on the 
surface of distilled water for a variety of periods of from 
about ten minutes to fourteen hours and then fixed. On 
March 4 a similar series was made, which extended the 
period to twenty-four hours. From the cultures sown in 
the middle of January, prothallia were used on March 23 
to extend the period to thirty hours, and on April 23 to 
seventy-two hours. Prothallia from each series were sec- 
tioned, but in none of them were any embryos or signs of 
1 Campbell ’95, p. 407. 
