468 Stevens . — Spore Formation in Botrychium virginianum. 
mapped out by the kinoplasmic spindle) is not a constant state, but is 
engendered at the time of nuclear division. The gradual evolution of the 
spindle-fibres, in many cases without definite orientation at first, may 
be interpreted in this way. The force in play during cytopolarity seems to 
emanate from the nucleus, and particularly from the chromosomes, whether 
united into the nuclear thread or distinct during the later prophases and 
thereafter. The evidence for this is found in the facts that the axis of the 
poles always passes through the nucleus, and the spindle-fibres arise first in 
the nucleus or in the cytoplasm in definite relation to the nucleus ; and 
in pollen- and spore-mother-cells after the second maturation-division 
kinoplasmic connecting fibres spring up between and connecting the pairs 
of granddaughter nuclei preparatory to the formation of the cell-plates 
(see my Figs. 37 to 40 inclusive, and, without seeking further, Mottier’s 
Fig. 50 in Cytologische Studien). That the chromosomes have the dominant 
part in this appears from the fact that the nucleus as an entirety has 
in so many instances disappeared, leaving only the chromosomes to repre- 
sent it, before polarity has become completely established (see my Figs. 9 
to 1 5 inclusive, and Osterhout’s and Mottier’s Figures in Cytologische 
Studien). This conjecture receives further support from those cases where 
the second division takes place without the formation of a resting daughter- 
nucleus. 
In Botrychium , as the chromosomes of the first division approach 
the poles the spindle-fibres form a dense cone, as shown in Fig. 24. 
Apparently the chromosomes are being drawn toward the pole by a con- 
traction of the fibres. I see nothing in my preparations to indicate that 
the anaphase translocation of the chromosomes is brought about in any 
other way. (For a summation of the evidence on which he grounds 
his opinion of chromosome translocation by a contraction of the spindle- 
fibres see Strasburger, *00, pp. 140-2 ; and for a resume of the different 
theories regarding this subject see Hacker’s Praxis und Theorie der Zellen- 
und Befruchtungslehre, pp. 73- 8). 
Arrived at the poles the chromosomes fuse together, and the daughter- 
nuclei enter upon a resting-stage in which the chromatin becomes again 
cyanophil, forming a fine-meshed reticulum, and one or more nucleoli 
appear (Figs. 25-8). 
While the daughter-nuclei are entering into the resting-stage the connect- 
ing fibres are spreading out along the equatorial plane (Fig. 26), and in the 
equatorial zone, deposits of granules are accumulating which are stained 
from grey to brownish by the three-colour method (Figs. 26-8). The 
connecting fibres disappear soon after they have traversed the equatorial 
plane, and the resting-stage then appears as in Fig. 28. It is seen that 
no cell-plate of the usual kind is formed, but in its place is a broad and 
dense zone of cytoplasm. 
