''CrnIi.&'S?l!i'8S'] Microscojjical Frejjarations. 157 
marked line of separation can be seen marking the boundary of the 
growing point, the cells being deeply coloured for a short distance. 
The cells are densely filled with granular protoplasm, and each 
contains a very large nucleus. A httle higher up the colouring 
gets very faint, and at last is confined to the interior of the rootlet, 
v^here a few nuclei are seen closely surrounding the spiral vessels. 
The growing point of a root of the Phalaris, when treated with 
carmine, shows — 1st. A number of large loose cells at the point, 
extending like a pileorhiza, a short distance from the extremity ; 
2nd. The internal cells of this sheath are coloured, and therefore 
contain active protoplasm ; 3rd. The growing point of the root is 
very deeply coloured, the protoplasm is densely granular, and con- 
tains a large nucleus ; 4th. A very short distance above the growing 
part the cells are only marked by an occasional nucleus ; and, lastly, 
the nuclei are only found close to the spiral vessels. 
B. Experiments with Sinapis alba {White Mustard) — Series 1. 
— These were begun in February, 1868, and consisted in germina- 
ting white mustard both in water and in soil, and then examining 
the structure after staining with carmine. During the first stages 
of germination of the seeds, germinated both in soil and in water, 
no trace of staining could be found, and it was not till the radicle 
had attained some size that the point of the root became stained 
with the carmine. If we can depend on such tests, we must con- 
clude that the germination of the white mustard is not dependent 
on the formation of new cells, but merely on the growth and en- 
largement of the pre-existing cells. Whenever growth by the 
formation of new cells had taken place these cells could be rendered 
distinctly visible by the action of carmine, the parts above this 
remaining white, although submitted to the action of carmine under 
precisely the same conditions. 
Series 2. — A much more extensive series of experiments was 
tried in December, 1868, by growing white mustard for a short 
time in carmine solution. After the plants were about two inches 
in height carmine was added, and they continued to grow for 
several days after. The youngest stages of development failed to 
furnish stained specimens, and it was only after a few days that the 
young radicles could be stained. The structure of the root is more 
complex than that seen in the Fh alar is canariensis, but agreed in 
every essential point. The loose cells were seen at the tip, the 
growing point densely coloured, the colouring becoming less and 
less till it was no longer visible. The protoplasm near the growing 
point is densely granular, and the nuclei very large, filhng up from 
one-fourth to one-third of the whole cell. 
Transverse sections of the young root, above the growing point, 
showed the arrangement of the cells very clearly. In the centre is 
a mass of small thickened cells, containing protoplasm and nuclei 
