Shaw . — The Fertilization of O nocle a. 269 
the fact that the first division of the egg takes place nine 
or ten days after fertilization, more of the older stages from 
Series I were sectioned and the following young embryos 
were found : — 
Embryos of Onoclea Struthiopteris- from Series I. 
Fertilized 9 days, 3 embryos of 2 cells. 
( 2 „ 2 „ 
r> JO » \ 2 jj 4 v 
' 1 „ « » 
On March 18 both box cultures were flooded (one had 
been half-flooded before), and from each specimens were 
fixed daily to form a series, one covering fifteen and the 
other twenty days. With thermometers, which hung near 
the cultures, the temperature of the room was noted each 
day when plants were fixed, and recorded with the maximum 
and minimum temperatures for the preceding twenty-four 
hours. It ranged from io° C. to 25 0 C. The material 
yielded the following : — 
Embryos of Onoclea Struthiopteris from Series IV and V. 
embryos of 4 cells. 
1 
» 
6 
33 
Fertilized 10 days 
1 
53 
15 
33 
2 
>3 
1 6 
33 
^1 
33 
17 
33 
„ 12 ,, 
1 
>3 
16 
33 
The results were enough to satisfy the writer that, under 
favourable conditions in the laboratory, the egg of Onoclea 
Struthiopteris is not likely to divide sooner than a week after 
fertilization ; and they indicated that uprooting, handling, 
and replanting the prothallia did not retard the formation 
of the embryo. 
After the embryos of O. Struthiopteris had been found, 
attention was again turned to the longest series of prothallia 
which had been killed in 1896, and by sectioning a large 
number of prothallia the following were obtained : — 
