THE STORAGE OF RESERVE MATERIALS 237 
oil plant in which some of them are lying. The figure 
represents the cell after treatment with alcohol, and subse- 
quently with water. The alcohol removes the oil with 
which the cells are filled, and which obscures the appear- 
ance of the grains. The latter are of ovoid shape, and as 
they lie their structure is not apparent. Water dissolves 
part of the outer portion, leaving visible the ovoid body, 
which becomes transparent. Embedded in it are a large 
regular crystal of protein matter, and a small rounded 
irregular mass of minute crystals of mineral matter. These 
two constituents are spoken of as the crystalloid and the 
globoid respectively. The part of the matrix which is not 
soluble in water will dissolve in a 10 per cent. solution of 
common salt, while the crystalloid is soluble only in a 
saturated solution. The globoid of the grains of the castor- 
oil plant is a double phosphate of magnesium and calcium. 
Examination of these grains and their reactions shows 
that several proteins can be detected in them. Those 
soluble in water are proteoses, while the others which 
dissolve only in salt solutions are globulins. In grains 
met with in other plants, metaproteins occur which dissolve 
only in dilute alkalies. 
Crystals of protein occur in other places than seeds. 
Ii we examine a young potato, we find, in certain cells 
lying a little below the skin, some regular transparent 
cubical crystals, which are composed apparently of the 
same material as the crystalloids of the complex aleurone 
grains described. They are soluble in saturated solutions 
of common salt. Similar crystals are met with in the 
tissues of certain seaweeds. Many of them can be made 
to crystallise from the solvents which are used to extract 
them. 
The seeds of the cereal grasses contain two other very 
curious reserve proteins, which give rise in the flour to a 
peculiar sticky material which is generally known as 
gluten. They do not appear to be present in the aleurone 
grains of the seeds, but to occur in the starch-containing 
