1899] CURRENT LITERATURE 489 
in the cell capsule and spores, which accordingly stain with iodine while the 
asporogenous cells are glycogen free (S. [A/ycoderma] orientalis) and do not 
stain by iodine. 
2. Spore-bearing colonies liquefy gelatin usually much faster than spore- 
free colonies. 
Colonies with spores are often snow-white, while the spore-free 
colonies are colored watery-brown.— H. E. DAVIEs. 
THE KARYOKINETIC division of the nucleus of A//ium Cefa has been 
further investigated by Némec.’?__In studying the formation of the achromatic 
spindle he finds that it does not begin as a multipolar affair, as found in other 
plants by Mottier, Osterhout, and others, but is bipolar from the beginning of 
its formation. Threads which appear just outside the nuclear membrane are 
soon seen to be drawn out into poles at opposite sides of the nucleus. The 
spindle fibers of either pole may be of unequal length, but all converge 
toward a common point. Some of the figures suggest that other interpreters 
might claim for them the condition of multipolarity. The nuclear membrane 
does not often disappear until the achromatic spindle is almost formed, and 
there is no evidence justifying the statement that it contributes to the forma- 
tion of the spindle. The form of the spindle is determined by the dimen- 
sions of the dividing cell. The development of spindles in cells of the 
plerome shows characteristic differences from the same process in cells of the 
periblem. 
At about the time the nuclear membrane disappears the chromatin thread 
breaks up into a few divisions, and these again break up forming the chromo- 
somes, If the chromosomes are short they are placed parallel to the spindle 
threads, while if they are long there is no regularity in their position. Some 
spindle fibers pass directly from pole to pole, while others are attached to the 
chromosomes. The chromosomes split longitudinally, beginning at the looped 
end. After the pairs of chromosomes have divided somewhat, aha are 
seen connecting them, and Né hat th fik lyd ent in 
_ structure from those which first formed the spindle. T hey are thicker, more 
_ granular, and stain more like chromatin than the earlier formed fibers. As 
to their function, he says any statement would at present be a mere guess, 
but suggests that, by exerting a push, they may assist the fibers which are 
pulling the chromosomes. 
_ Structures which have been described by some other writers as centro- 
somes are represented in the drawings, but the author thinks they are nucleoli, 
and are finally enclosed within the nuclear membrane. 
The statement is made that the chief morphological difference between the 
division of cells of vegetative tissue and those of sporogenous tissue consists 
g in der Wurzelspitze von Allium cepa. 
7 Ueber die karyokinetische Kerntheilun 
Jahrb, f. wiss. Bot. 33 : 313-336. 1899. 
