Rivett—The Cy fop/asm in the Cells of Alicularia sc alar is. 209 
Thus we find that the numerous small drops have coalesced into fewer 
larger bubbles. These are still within the substance of the protoplasm, 
separated from the cell-sap by a protoplasmic membrane. This is not 
visible owing to the refractive glimmer of the oil. 
In the mature cells, i. e. those of the fully grown leaves, the large oil- 
bodies are visible. They protrude from some point on the cell-wall into the 
central vacuole; it is obvious from their position that they are bounded by 
a surrounding sac of protoplasm which is continuous with the primordial 
utricle lining the cell-wall. Thus the two secretions of the protoplasm—the 
cell-sap and the oil—are separated from one another by a partition of the 
mother substance. In these mature cells there are still to be seen the 
moving refractive granules found in the youngest living cells. 
From these simple observations on the living material but few 
deductions can be made. There is certainly a suggestion that the oil 
originates as a general protoplasmic secretion, which appears as a series of 
bubbles ; there is nothing to indicate that any special body (or elaioplast) is 
associated with each bubble or that the bubbles are localized to any particular 
part of the protoplasm; in fact, appearances are rather against such a view, 
because the numbers and disposition of the first-formed bubbles differ 
greatly in different cells. On these grounds both the small drops and later 
the coalesced larger drops can be termed oil-vacuoles, since they are nothing 
but spaces in the protoplasm filled with the oily liquid. Their formation is 
quite similar to that of the central vacuole, for the secretion of the drops one 
by one and the maintenance of their identity for some time are simply due 
to the physical properties of the liquid oil and its non-miscibility with the 
more fluid cell-sap; there is nothing to prove that the cell-sap is not 
secreted drop by drop within the protoplasm and afterwards collected into 
the large drop which fills the central vacuole. Whether the lining layer of 
protoplasm in contact with the oil is in any way changed by the contact or 
by its own act of secretion, so as to form a definite membrane, different in 
physical and chemical properties from the rest of the cytoplasm, cannot 
be determined merely by simple observation. 
The nature of the oil in the oil-bodies is agreed upon by all investigators 
as a mixture of an ethereal oil with a small quantity of fatty oil and a proteid 
substance. This is proved by the action of alcohol, which will, in the cold 
state and diluted with water, dissolve the greater part of the oil with rapidity. 
If a leaf is treated with caustic potash, or with a mixture of caustic potash 
and ammonia, or with a solution of sodium carbonate, the oil-bodies do not 
lose their refractive properties; i. e. they do not saponify and therefore do 
not consist mainly of fatty oils. After treatment with alcohol it is always 
found that there is a small insoluble residuum consisting of an emulsion of 
small drops with a high refractive index: this seems to be partly a fatty 
substance and partly proteid. From the homogeneous appearance of the 
P 
