484. ARTHUR BOLLES LER. 
such as those of the nuclei of Amphibia, are derived from the un- 
segmented filament. The filament is here fine, very long, closely 
convoluted. It is also extremely delicate, and where its convo- 
lutions cross and touch they adhere and fuse, forming nodal 
thickenings (‘‘nucleoli”’ of some authors). But the filament 
none the less remains essentially autonomous, as is proved by 
its disentangling itself from this seemingly inextricable maze, 
and appearing in the well-known skein form or “ convolution” 
of the first phase of karyokinesis. These networks of the 
Amphibian nucleus are real anatomical structures; but the 
chromatic networks, believed to exist in other groups, are for 
the most part either artifacts—adhesions of the loops of the 
filament being brought about by the reagents employed or by 
pressure—or they are mere optical simulacra of networks, 
brought about by insufficient resolving power in the objectives 
employed, or by faulty microscopic manipulation. 
Is the doctrine just stated a true one? I have satisfied 
myself by my own observations that it is, and that the belief 
that the normal typical form of the chromatic element is that 
of a network is an “Idolon spelunce,” bred of too- 
exclusive dwelling in the cave of Salamandra. I think the 
question is mainly one of pure micrography, a matter which 
everyone must settle for himself with his finger on the fine- 
adjustment screw. Want of space forbids me to say more on 
the subject at present, and I can only remind the reader that 
the doctrine of a continuous nuclear filament is held, with 
certain modifications, by Balbiani, by Strasburger,! and by 
Rabl.? 
The chromatic filament is embedded in an achromatic ground- 
substance, “ Kernsaft,” “suc nucléaire” of French writers, 
“caryoplasma” of Carnoy. What is the nature of this 
substance? Say the authors in general, it is a structureless 
juice. Says Carnoy, with Pfitzner, it has structure. It consists 
of a reticulum (‘reticulum plastinien” of Carnoy, “ para- 
1 «Ueber den Theilungsvorgang, &c.,” in ‘ Arch. f. mik. Anat.,’ 1882, and ~ 
“ Die Controversen, &c.,” ibid., 1884. 
2 «Morphol, Jahrb.,’ 10ter Bd., 2 Hft., 1884, 
