6 PROPERTIES OF PROTOPLASM. 
Physical Properties of Protoplasm.—Protoplasm, 
or living matter, is in itself usually colourless and trans- 
parent. Its consistency varies considerably according to 
the amount of contained water. There can be little doubt 
that it is a physical as well as a chemical complex. 
Differential staining and other methods reveal the existence 
of a meshwork of more stable and less fluid substance, 
sometimes termed sfongioplasm, and a more mobile and 
less easily stained substance, sometimes termed hyaloplasm, 
which permeates the interstices of the spongioplasm. 
Scattered throughout the hyaloplasm is a number of 
minute bodies, readily stained and of unknown com- 
position. They are called microsomata and may be con- 
nected with the nutrition of the more essential living parts 
of the protoplasm, as they decrease and are absorbed when 
the protoplasm is starved. This idea is often extended to 
include the hyaloplasm, which is thus regarded as merely 
a nutrient fluid bathing the primary living spongioplasm, 
but there is little certainty regarding these points. It is 
important to notice that at least three physical constituents 
of protoplasm can be discerned, and that its mobility, 
fluidity and reactivity are directly related to the amount 
of contained water. A number of the physical phenomena 
of protoplasm, such as its mobile movements and change 
of shape, can be closely imitated by small isolated oil 
drops and other devices. 
Chemical Properties of Protoplasm.—It is very 
generally accepted that protoplasm is not a definite 
chemical substance but a complex of several. If it be a 
single substance it must be of so great instability as to 
break up into its constituents as soon as it is formed. 
Analysis shows that protoplasm consists of a number of 
substances called fro¢edds, which are sufficiently definite 
to come within the power of chemical manipulation. They 
may be the first decomposition-products of protoplasm 
itself, or they may be the actual constituents of protoplasm. 
In other words, protoplasm is either a physical or a chemical 
aggregate of proteids. 
Proteids are of very complex molecular composition, and are 
known by definite chemical tests (such as the production of a violet 
