The individuality of the cliromosomes and their serial arrangement, etc. 1 15 
fixcd at various dates during the growing season. Flower spikes were 
collected three or four times a week from the time the first leaves appeared 
imtil the poUen was shed. Both root tips and male and female flower 
spikes were fixed in the Flemming chrom-osmium-acetic Solutions. The 
strong, medium, and weak strengths were all used. The best results 
were obtained with the strong for the root tips and the medium for the 
anthers. To secure good penetration of the flower spikes they were 
first dipped in Carnoy’s fluid, or split lengthwise, or the glume-like 
bracts subtending the staminate flowers were removed. Flower spikes 
were also fixed in piero-formol solution with rather good results. The 
imbedded material was cut in sections from four to eight ft thick. For 
staining, the Flemming triple combination was used almost exclusively, 
although a few slides of each of the best series were stained with iron- 
haematoxyhn. It was found that better staining results were secured 
when Merck’s “perhydrol” diluted in 70% alcohol to a strength of 3% 
was used as a bleach instead of commercial “dioxogen”. 
Description of observaiions. 
The Resting Nuclei. 
The resting nuclei in the embryonic region of the root tips are rather 
large in proportion to the size of the cells. One, two, or three nucleoles 
may be present as conspicuous spherical bodies. The chromatin appears 
in these resting nuclei in the form of small but definite oval masses, the 
“pseudo-nucleolen” of Zacharias (1895) and Kosenberg (1904), “chro- 
mocentren” of Rosenberg (1909 b) or the “prochromosomes” of Over- 
ton (1905). These masses are distributed rather evenly about the peri- 
phery of the nucleus. Aside from these chromatin masses with the con- 
necting Strands of linin and the nucleoles, the entire nuclear ca\ity appears 
to be filled with a homogeneous achromatic substance. The nucleoles 
may lie near the center or to one side of the nucleus. The chromatin 
masses are distributed rather evenly about the periphery of the nucleus. 
In well stained preparations it is also e^ddent that these masses are con- 
nected together in longer or shorter series and do not form a reticulum 
such as has been commonly described for the resting nuclei. The serial 
arrangement is not always easily recognized at this stage, but by careful 
study it can always be observed, at least in certain parts of a nucleus. 
It is difficult to represent this arrangement in drawings. In my figures 
the chromatin masses lying in the higher focal planes are drawn darker, 
but the windings of the series cannot be brought out fully. 
8 * 
