164 W. WALDEYER. 
(resting nucleus), consists of a network of distinct threads 
or strings, some finer, some coarser, the arrangement of which, 
according to the figures and descriptions of most authors, 
does not reveal a definite regularity or constancy. Some 
writers, on the other hand, such as Balbiani (9) and Flemming 
(58), Biitschli (44), Rabl (165), and others, have made out a 
special and regular arrangement of threads in nuclei of certain 
organs and in certain animals. Balbiani and Rabl go so far 
as to assume a regular arrangement as universal for all resting 
nuclei, but no generalisation can be formulated in regard to 
this. For example, Balbiani found in Chironomus-larva only a 
single greatly coiled thread in the resting nucleus. Flem- 
ming is inclined to regard this as a widely spread occurrence. 
Others dispute this (see below). Again, it is still doubtful if 
the threads, whether there be oneor many, arenon-anastomosing, 
or if there exist net-like anastomoses between the separate 
coils, in other words, a network (as in fig. 1). Were there a 
regular arrangement of threads in every existing nucleus, it 
would be of great importance in the interpretation of the phe- 
nomena of karyokinesis. Rabl has, indeed, expressly pointed to 
such an interpretation of the network of resting nuclei. He 
distinguishes “ primary ” from “ secondary ” nuclear threads ; 
the former are longer and mostly arranged excentrically in the 
nucleus, and extend round the surface of it in such a way 
that at one point of it—the “ polar-field”” (Rabl)—they form 
loops, the apices of which are placed round the pole, whilst 
their free ends extend nearly to the opposite side, where a 
different arrangement is recognisable. This side of the nucleus, 
in which a polar area is not present, is called by Rabl the 
‘‘Gegenpolseite ” (antipole). Figs. 2, 3, and 4 serve to explain 
this. In fig. 2 the angles of the loops are directed towards 
the pole; in fig. 3 the ‘“‘ antipole”’ is represented. Neither 
figure, however, applies to the resting nucleus, but to the first 
stage of karyokinesis, the so-called ‘‘ dense skein” (“ dichter 
Kniuel”), where the secondary threads have disappeared 
and the primary threads are so prominent that the whole 
arrangement is distinct. Fig. 4 shows on the right side of 
