532 Lewis . — The Behaviour of the Chromosomes 
of the cavity, but a few chromomeres may be seen lingering behind. Linin 
threads pass out toward the nuclear membrane, and the whole gives one the 
impression that the content has simply contracted. There is at this time 
no structure which can be regarded as a continuous spirem (Fig. 2). The 
contraction continues, the elements retaining the same structure and stain- 
ing reactions, and in such nuclei there can be no doubt of the manner 
in which the chromatic content approaches synapsis. There is no indi- 
cation of a pairing or conjugation of the chromomeres or of the linin 
threads, but rather a contracting of an irregular reticulum of single threads 
studded throughout with single chromomeres (Fig. 3). Before the greatest 
degree of contraction is reached the chromomeres give evidence of dissolution 
into the smaller granules of which they are composed. These granules are 
apparently drawn out along the linin strands, numerous cross strands are 
drawn in, and the reticulum seems to be passing over into a skein or spirem 
(Fig. 4). The content stains more uniformly now than prior to this time. 
Following this condition the contraction becomes so dense that even in the 
best differentiated preparations it is impossible to observe clearly what 
takes place (Fig. 5). One can only observe the phenomena leading up 
to this condition and the recovery from it. 
Synapsis has been, and still is, variously interpreted by different 
workers. That it is a perfectly normal step in the process of reduction 
seems now to be generally agreed, Schaffner (’07) being perhaps the only 
investigator who still maintains the view once prevalent that this condition 
is an artifact. It must be admitted that the nucleus is at this time the seat 
of great activity, that the nuclear cavity is enlarging to its final size, and 
that conditions are therefore favourable for faulty fixation. But when one 
considers the differences between the structure of the nuclear content as 
it passes into this condition and as it recovers from it, together with the 
uniformity with which it occurs during the reduction division, and the fact 
that it has been frequently observed in living cells, the last objection seems 
to fall. 
The term synapsis has come to be used in a different sense from that in 
which it was first employed by Moore (’95). This writer was the first to call 
attention to the fact that the unilateral massing of the chromatic content of 
the nucleus is a normal step in mitosis. At that time, although all other 
investigators held this condition to be purely an artifact, Moore expressed 
the belief that whatever synapsis might eventually turn out to be, ‘ it is 
evidently a cellular metamorphosis of profoundly fundamental character,’ 
and, judged in the light of present interpretations, he could not have made 
a better supposition. The term synapsis was used by Moore to denote 
a definite stage or phase of mitosis, the meaning of which was not known 
and only in a vague way conjectured. Its application to this phase was 
soon adopted, and all investigators, whether recognizing the stage as normal 
