1238 General Notes. [December, 
reagent it acts like an albuminoid. This filament appears to have 
the chemical characters of nuclein; it is identical with the chro- _ 
matin of Flemming, and is the structure which takes so character- 
istic a share in the process of cell division. Carnoy insists, in 
contradiction of Flemming, that the nuclein or chromatin sub- 
stance is not characteristically in the form of a net-work, but con- 
sists of a single complexly convoluted fibril. The filament may 
occasionally form a true reticulum, but this is an unimportant 
modification of the typical single thread structure. The nuclein 
filament may alter and undergo a retrograde metamorphosis with 
age, and in cases completely disappear; in this process the fila- 
ment breaks up into irregular pieces which may be gradually 
absorbed. The presence of the nuclein filament is the only thing 
which distinguishes the nucleus either chemically or structurally 
from the rest of the cell. After solution of the nuclein or chro- 
matin filament, a second structure is discovered in the nucleus, 
namely, a fine reticulum which has all the characters of that 
previously described as existing in the extra-nuclear protoplasm. 
n his later work, Flemming is said also to have admitted the 
existence of this intra-nuclear net-work. The wall of the nu- 
cleus is imperforate and, in contradistinction to Klein, there is no 
direct union between the nuclear and extra-nuclear reticulum of 
fibrils. The reticula are much more resistant towards solvents 
than are most albuminous substances. The fibrils of the nucleus 
and contractile it becomes much the most resistant part of the 
_ cell toward reagents, even more so than the substance of the re- 
ticulum itself. The membrane, like the cell matter, is made up 
of a close reticulum of fibrils whose interstices are filled by a 
: more fluid substance. By a series of insensible gradations the 
protoplasmic membrane may be differentiated into a rigid, inert 
cell envelope. The various markings which are so striking a 
ature in the walls of many cells, both animal and vegetable, 
aD. owe their foundation to this complicated structure of the 
distinct kinds have been confused together by 
