34 
HISTOLOGY OF VEGETABLES. 
granules of a brown colour. In many of the cells, a 
large circular nucleus or cytoblast is present. In other 
parts of the same Potato , in 
which the disease is further ad- 
vanced, not only is the starch 
absent, hut a moniliform fun- 
gus, as shown in Fig. 23, oc- 
cupies many of the cells, and 
threads its way between others. 
In this section, the parts con- 
taining numerous brown gra- 
Portion of diseased Potato with nules exhibit the greatest num- 
fungus. ° 
ber of fungi. 
The next, and one of the most common of all the 
cell-contents, is known as chlorophylle. It has been 
before alluded to as the cause of the green colour of 
plants, and exists in the leaves and young stems of 
almost all the flowering plants, when not deprived of 
the action of light. 
Chlorophylle is soluble in alcohol and ether, but is 
not acted on by water. It forms a thin coating to the 
granules found in the interior of cells, some of which 
are said to be composed of mucilage, and others of 
starch, as is proved by their being rendered blue by 
iodine. That most remarkable phenomenon, the circu- 
lation of the contents of vegetable cells, or, as it is 
technically termed, cyclosis , may be examined at the 
same time as the chlorophylle granules ; the specimens 
selected for this purpose being either transparent water- 
