1900] ACHROMATIC SPINDLE OF OSMUNDA 367 
invading alcohol. Both cytoplasm and nucleoplasm were pushed 
forward ; but no one could mistake such a condition for synapsis 
if he had once become acquainted with the latter. Contrary to 
what might be looked for, it was the resting cell which suffered 
most by this treatment; the spindle fibers, the chromosomes, 
and the spirem thread were not seriously affected. 
It will now be necessary to refer briefly to intranuclear 
changes. The chromatic material, emerging from synapsis, 
gradually unrolls and extends itself within the nuclear cavity 
into a much coiled spirem, apparently of one continuous thread, 
forno ends can be seen in uncut parts of the nucleus. The 
spitem shortens and thickens, and after a time is segmented into 
long irregular chromosomes, which continue the shortening and 
thickening process already begun in the spirem. It is easy to 
see that many of the chromosomes are split longitudinally into 
pairs, and the two parts of a pair are often twisted loosely about 
fach other. They take up a peripheral position in the nucleus, 
being apparently in close contact with the nuclear membrane, 
= halves usually remain attached to each other for a time, 
iving rise to Xs and Ys, or loops (as in fig. 5), according to the 
mode of attachment. But while the shortening is still going on, 
‘ome of the pairs fall apart; otherwise how can the number of 
chromosomes shown in fig. 7 be accounted for, if Strasburger’s 
\15) estimate of twelve? be correct? This number has been 
‘ounted in a few cases in uncut nuclei of the age shown in fig. 5. 
ad also in polar views of the late anaphase in which twelve 
ughter chromosomes have been seen symmetrically grouped 
tthe pole. But in nuclei of the condition shown in fig. 7 
the Number of separate chromatin masses is quite variable, four- # 
aoe or sixteen being most common, and even as a 
_, osnty have been counted.3 If these numbers indicate a fa 
ing “Part of some of the chromosome pairs, there must be a ae 
| Sig reunion before their arrangement into such an ee 
“S that shown in fig. 8, in which of the twelve chromati 
| See Rote at the end of the paper. 
3Guj 
8nard counted as many as twenty-two. 
