488 Farmer. — On Spore-Formation and 
The linin goes through none of the evolutions which dis- 
tinguish the first heterotype mitosis, but becomes visible as 
a thickening thread which is divided into eight segments. 
These double upon themselves, and so resemble V’s whose 
limbs are nearly, or even quite, in contact. They place them- 
selves on the spindle with their angle directed centrally, and 
at once split longitudinally. But the fission, thus deferred 
beyond the time usually assigned to even homotype divisions, 
is not at first complete through the entire length. It com- 
mences at the angle, and the split portions at once diverge 
polewards along the spindle-fibres. Thus an appearance is 
produced which irresistibly recalls that presented during the 
final separation of the segments of the heterotype chromosomes, 
and it is only the differences in their respective earlier stages 
which differentiates the one from the other. Further, a com- 
parison of Pellia with Fegatella , in which the spores also 
germinate while still within the sporogonium, conclusively 
shows that we are here dealing with a true, if somewhat 
aberrant, homotype mitosis. For the process of karyokinesis 
in Fegatella is almost diagrammatic in the regular and typical 
succession of the events and in the distinctness of the several 
stages. 
The nuclei of the sporophytic cells exhibit sixteen chromo- 
somes, instead of eight, when in the equatorial plate, and thus 
this plant furnishes another instance of the correctness of 
Overton’s view as to the correspondence of the reduction in 
the number of these bodies with the periodic alternation of 
generations. 
I observed a slight amount of variation in the number of 
the chromosomes in the nuclei of the germinating spores 
(gametophyte). Thus in two cases there were certainly nine, 
and not eight chromosomes as in the great majority of the 
nuclei, and in one case I could only count seven. This last 
instance was taken from a very good preparation, and I do 
not think that there was any reason to think one chromosome 
had become displaced or that it had been so obscured by 
another one that I missed counting it. But these facts do not 
