265 
Shaw. — The Fertilization of Onoclea. 
of the oogonium of Chara with a view to finding the sperm a- 
tozoid on its way to the egg-nucleus. In the species which 
were studied, no sign could be found to indicate at what stage 
the spermatozoid entered the oogonium, and no spermatozoids 
were found in the sections. At that time Dr. D. H. Campbell 
suggested that some of the Ferns would be better subjects for 
following the stages which were sought, and he kindly supplied 
spores of Marsilia vestita and also another species of Marsilia 
( M . . Drummondii ?) from Australia and Onoclea sensibilis. 
When the spores of Marsilia are sown in water, the 
prothallia become fully developed in about fifteen hours 1 
at ordinary temperatures ; at the end of that time the 
spermatozoids are set free, and make their way to the 
female prothallium and through the large mucilaginous funnel 
to the archegonium, where they sometimes arrive before that 
organ is open. The first division of the egg takes place 
within about an hour 2 after the entrance of the spermatozoid 
into the archegonium. It was found difficult to mark the 
exact time at. which the spermatozoid enters. While en- 
deavouring to become sufficiently familiar with the plant to 
overcome this difficulty the writer found that in some cases 
the oospores of the Australian Marsilia developed into 
embryos without any evidence of the presence of sperma- 
tozoids about the archegonia. The spores had been sown 
about ten o’clock at night, and were first examined about half- 
past eight the next morning. No spermatozoids were seen 
during that morning, and there were no remains of sperma- 
tozoids about the mucilaginous funnel in front of the arche- 
gonium. The prothallia were kept, however, and after a few 
days they were found to bear gmbryos of considerable size. 
This suggested the idea that the embryos might have been 
developed without fertilization, and a short series of ex- 
periments 3 was made with isolated macrospores for the 
purpose of testing the matter, and indicated that such was 
1 Campbell ’95, p. 405. 2 1 . c., p. 407. 
3 Shaw ’97, p. 1 14. 
