in Lilium Martagon : II. Spermatogenesis . 203 
and in such cases the twist of the segments on each other can 
be made out (Figs. 11 and 11 a). When the twist is tight, the 
loops may appear as circular dots in the otherwise seemingly 
solid chromosome, or no loops at all may be visible. This is 
particularly apt to occur in preparations from material fixed 
with absolute alcohol. The real structure may be demon- 
strated in such cases — at the cost of the preparation — by 
first treating the nucleus with warm $o°/ o acetic acid to clear 
the structure 1 , and then allowing fuming hydrochloric acid to 
run in under the cover-slip 2 . The cellulose and cytoplasmic 
structures have all been more or less dissolved by the acetic 
acid. The chromosomes stand out, their structure unaltered, 
but with a peculiar highly refractive appearance. It is well 
to choose a particular chromosome for observation under 
a high power before running in the fuming hydrochloric acid. 
The action of this reagent is very sudden. The chromosome 
retains its solid homogeneous appearance for some time, but 
then swells up, and for a few moments shows two spongy 
segments, each clearly outlined by a broken black line. The 
twist of these segments on each other is quite clear, but the 
whole chromosome disappears very quickly. Chromosomes 
fixed in Hermann’s solution cannot be dissolved in this way. 
The disappearance of the nuclear membrane and the forma- 
tion of the spindle can often be beautifully traced in the 
mother-cells of a single loculus. Fragments of nucleolar 
matter can sometimes be seen among the chromosomes after 
the nuclear membrane has gone. At the same time a number 
of large erythrophilous granules appear in the cytoplasm 
(Fig. 10 a). These are doubtless of nucleolar origin. 
The chromosomes seem driven together in a heap on the 
disappearance of the boundary between nucleus and cytoplasm 
(Fig. 10 a). The spindle-fibres soon make their appearance 
at two or three points in the cytoplasm (Fig. 10 a), whence 
1 E. Zacharias, Ueber das Verhalten des Zellkerns in wachsenden Zellen, Flora, 
1895, Erganzungsband, p. 241. Quoted in Zimmer mann’s Morphologie und 
Physiologie des pflanzlichen Zellkernes, 1896, p. 27. 
2 Strasburger, Ueber Kern- und Zelltheilung, 1888, p. 146. 
