Oogenesis & Embryogeny in Ephedra distachya.i 75 
In one archegonium both normal and abnormal pro-embryonal 
cells were found to be present. Pro-embryonal cells also occur 
within jacket cells which are not adjacent to the archegonia. 
Migration and fusion of the nuclei of neighbouring jacket cells 
precedes their formation. On dividing, these fusion nuclei show the 
sporophytic number of chromosomes. 
It seems possible from Jaccard’s account of Ephedra helvetica, 
that a similar development of the jacket cells occurs in that species 
also. Such development, if at all general in the genus, seems to 
indicate that, as in Welwitschia, a large proportion of the cells in 
the apical part of the prothallium are capable of fertilization and 
embryo-formation. 
In conclusion we wish to thank Miss Benson for much kind 
help during the course of the work. Figures 3, 5 and 6 (Plate II.) 
are taken from drawings made by her during Miss Sunday’s absence 
in South Africa. 
University College, 
London, 1907. 
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