Allen—Spermatogenesis and Apogamy in Ferns . 37 
To make certain that the same chromosome number persists- 
throughout the life of the sporophyte, sections were made of 
the young spore sac and the chromosome number in dividing 
nuclei counted in the same way. Division figures are easily 
obtained. Figure forty-two which was earlier described, shows 
an equatorial plate stage. The numbers obtained in the in¬ 
dividual countings in the young sporophyte were 61, 63, 65 ,—- 
ave. 63; 66, 63, 66 ,—average 65; 61, 65, 65, average 63. The- 
total average here is 65. 
The evidence is conclusive from all the above countings that 
the chromosome numbers from the nuclei of the prothallium, 
young sporophyte and sporange are approximately the same. 
The number characteristic of all these stages may then be 
said with considerable certainty to be between 60 and 65. 
Whether it is the original gametophyte number which per¬ 
sists through the sporophyte or whether it is the diploid sporo¬ 
phyte number which persists through the gametophyte is a 
question of considerable difficulty. 
General Discussion. 
Belajelf has described especially the transformation of the 
nucleus into a spiral form, but the change in form of the cell 
as a whole, the question as to the persistence of the plasma 
membrane, etc., are much less clearly worked out. 
In the antherozoid of the Gymnosperm the cytoplasm remains 
as a more or less rounded mass enclosing a large spherical nu¬ 
cleus. Here there can be no doubt that the entire cell is pres¬ 
ent in the mature antherozoid and that the plasma membrane 
is still intact. According to Belajelf, it is also intact in Chara. 
In Adiantum as described above, the plasma membrane forms 
an unbroken covering of the antherozoid. Here, however, as 
is usual in ferns, the bulk of the cytoplasm is at the posterior 
end. It is found there very early in the process of transforma¬ 
tion and remains there as the spiral is developed. The plasma 
membrane apparently shrinks in about the spiral nucleus 
throughout its whole extent. 
Ikeno, as noted above, concludes from his observations on 
