224 
W. C. TWISS 
more favorable conditions of temperature and light, prepared and stained 
by the Benda method, show a much greater proportion of the enlarged 
vesicular bodies which stain like mitochondria. In these preparations, 
however, there is very good evidence that these bodies are in reality plastids, 
since they show a lighter colored internal portion, evidently consisting of 
starch. In regions apart from the meristem these bodies are very abundant. 
In the plerome (fig. 4) the filamentous mitochondria often appear swollen 
at the ends or sometimes in other portions, while the plastids, ovoid or 
spherical in shape, may contain from one to several starch grains each as 
shown in figure 5. 
In the periblem, on the other hand, there are in the intermediate regions 
of the tip, ovoid, spherical, or irregular masses of a much more solid appear- 
ance, in general, but often showing a number of discrete spherical granules 
in their interior. Numerous smaller spherical or ovoid bodies are also 
present, scattered about through the cytoplasm, which are dark blue in 
color, taking the stain exactly as do the plastids and the filamentous mito- 
chondria. 
These preparations, stained and fixed according to the Benda method, 
as previously stated, show the nucleus finely granular in appearance and 
of an old-rose color, as dark, relatively, as shown in the drawings, figures 
4 and 5. The nucleole is apparently of a denser consistency and stains a 
darker shade of the same color. The cytoplasm is very well preserved and 
stains somewhat lighter than the nuclear material. 
A slide of the above described material was freed from parafiin with 
xylol, bleached for a few minutes in hydrogen peroxide, and treated with 
potassium iodide-iodine solution, with the object of testing for starch. 
Under this treatment the bodies which have been referred to as plastids 
show a bluish color in their interior, but hardly pronounced enough to be 
considered a convincing demonstration of the presence of starch. A sub- 
sequent treatment of the slide with a solution of iodine in chloral hydrate, 
however, gave better results, differentiating the bodies so that they appear 
as plastids with included starch grains, as indicated by the blue color of the 
interior. 
Next, a similar slide from the Benda fixation was stained with the 
Flemming three-color process, the red being left decidedly strong. The 
mitochondria, both granular and filamentous, are now strongly stained by 
the safranin, while the plastids are colored blue. In the intermediate regions 
of the tip, in the periblem area, the plastids are rather lightly stained, and 
within each of them there are a varying number of spherical granules which 
are stained by the safranin in the same manner as the mitochondria, except 
that they are, generally, a brighter red. In figure 6, a, b, c, d, and e, a 
number of these plastids are shown with their included red-staining granules. 
As one leaves the intermediate regions of the tip and proceeds toward the 
proximal portion, the red bodies within the plastids gradually lose their 
