40 Overton. — On the Organization of the N tic lei in the 
clusively prove the permanence of the chromosomes from one cell generation 
to another.’ 
Farmer and Moore (’05) have also observed in the cockroach that the 
limits of the chromosomes are usually visible even when the nucleus is in 
a condition of complete rest, although these bodies are not quite so 
definitely shown as in Triton . Moore and Walker (’05) have reported that 
similar chromosome primordia are also present in the meiotic cells of the 
guinea-pig. 
Recently Dublin (’05) has observed that the chromosomes of Pedi- 
cellaria persist from the telophases of the oogonia to the prophases of the 
ovocyte. 
Additional evidence of the permanence of the chromosomes has been 
brought out by the observations of Gregoire and Wygaerts (’03), Kowalski 
(’04), and Mano (’04) ; and the observations of Gregoire (’06, ’07) tend to show 
that in nuclei in which there is an apparent disappearance of each chromo- 
some during rest, they do, nevertheless, persist as individual or autonomous 
structures. The reticulum is formed by a progressive vacuolization and 
alveolization of each chromosome and union of these alveolized chromatic 
bands by lateral anastomoses. The chromosomes are, therefore, present in 
the nucleus as autonomous bodies, but in a different form from that in the 
division stages. The resting nucleus is then an ‘association de chromosomes 
alveolises et reticulises each of which again becomes homogeneous during 
the prophases. These prophases appear to Gregoire and his students to 
strongly support the hypothesis of chromosome permanence and indi- 
viduality. Haecker (’04) also believes that the resting reticulum is formed 
in a similar manner. In the epidermal cells of Siredon larvae he observed 
that the chromosomes of the telophase become alveolized from without 
inward, so that he was able to distinguish a peripheral ‘ grosswabigen 
Alveolenmantel ’ and an axillary ‘ gekornelt erscheinenden Chromatin- 
strang’, which later undergoes further alveolization. If these central 
granular strands had remained unalveolized a structure would remain by 
which one could absolutely identify each chromosome in the resting 
reticulum. 
The organization of the nucleus as described by Rabl (’85) involves 
directly the permanence of the chromosomes. A comparison of the position 
and form of the chromosomes during reconstruction stages in the epithelial 
cells of Salamandra , with their position and form during the prophases of 
division, convinced Rabl that the chromosomes do not lose their individuality 
in the resting nucleus, and that they appear in the same relative position 
and forms in which they entered the reticulum. In the resting nucleus 
Rabl believed he could find traces of the chromosomes, and described 
a distinct polarity of the nucleus, in which the chromosomes converge 
toward a definite point. Out of the resting nucleus the chromosomes again 
