280 Shaw. — The Fertilization of Onoclea. 
nuclei in various stages of mitosis than those which were 
not disturbed until they were fixed. 
In an early stage of the segmentation of the egg, an 
exception was found to the order of the divisions usually 
described x . This was in an embryo in which the epibasal 
octants had already formed, but the hypobasal quadrants 
w r ere separated by a median instead of a transverse wall. 
On one side of this two octants had formed, and on the 
other the nucleus was in the metaphase of division. In other 
cases the quadrant walls were more or less oblique. 
The absence of radiations in the cytoplasm of the egg 
during fertilization is a character in which the Fern resembles 
the lower plants in which the process has been described. 
Strasburger’s suggestion 2 that their absence in Fucus , where 
they occur during mitosis, may be due to the fact that the 
cell division does not immediately follow fertilization, will 
be equally applicable to this Fern if the radiations can be 
found during mitosis. We were led to expect from the 
accounts of fertilization in other plants that the sperm-nucleus 
would become more or less like the egg-nucleus before the 
two united. The entrance of the unchanged sperm- nucleus 
into the egg-nucleus in Onoclea is so notably different from 
what has been said to occur in the eggs of other Ferns, that 
a further study of these is very desirable. Marsilia and 
Pilularia , while presenting some difficulty with regard to 
regulating and marking the time at which the spermatozoids 
enter the archegonia, have the great advantage that the 
nutrition of the eggs is well provided for, and there are 
not several eggs to contest for the food from one prothallium. 
It was thought that the disadvantages of working with the 
Onoclea prothallia could be avoided by selecting young ones 
on which only one archegonium was ripe, but this was not 
found practicable when a large number were required. The 
unsuspected fact that the egg did not divide for more than 
a week after fertilization was the greatest hindrance to the 
1 Campbell ’95, p. 316. 
2 Strasburger ’97, p. 419. 
