Allen—Spermatogenesis and Apogamy in Ferns. 5 
as tiny granules with two or three fibres radiating from them. 
When first seen they were some distance from the nucleus. He 
reaffirms his earlier statement that the hlepharoplast is not a 
centrosome. 
Ikeno (57, 59) claims that in Marcharitia, centrosomes are to 
be found at the spindle poles during several divisions preceding 
the formation of the antherozoid hut that the centrosome comes 
at each division from within the nucleus. The centrosome is 
conspicuous during the last division and at its close migrates 
to a comer of the cell and elongates against the plasma mem¬ 
brane. Two cilia grow from it. A body which Ikeno calls 
the “Nebenkern” appears after the last division and disap¬ 
pears soon after. The nucleus comes to lie connected with the 
elongating centrosome. The whole cell and the nucleus and 
centrosome within it now elongate to a spiral of one or two 
coils. 
Yamanouchi 1908 (102) finds in Nephrodium molle that 
the blepharoplasts first appear as well defined spheres in the 
cytoplasm on opposite sides of the cell just prior to the last 
division in the antheridial sac. The blepharoplasts remain 
near the spindle poles during the last division. Then the 
hlepharoplast applies itself to the nuclear membrane and elon¬ 
gates together with the nucleus to a spiral. In the mature 
antherozoid, the hlepharoplast runs two-thirds of the length of 
the spiral and cilia spring from its whole surface. 
The widespread occurrence of Apogamy in ferns together 
with the fundamental problems involved have led to consider¬ 
able investigation in this field. The earlier studies by Far- 
low, De Bary and others were models of accuracy and careful 
work and the observations of these authors have been almost 
wholly confirmed by more recent students. 
Farlow (35) discovered in 1874 that prothallia of Pteris 
cretica produce sporophytes directly by vegetative growth. Ac¬ 
cording to his description, the prothallia hear numerous antheri¬ 
dial sacs hut no archegones. A projecting mass of cells forms 
on the ventral side of the prothallium a few cell's hack from 
the apical notch. There is no definite boundary between the 
