THE ORGANIC CELL 
27 
have sought to show that all protoplasm, from whatever source 
obtained, possessed a common form of structure. No definite 
result has followed. In many forms of protoplasm, both in 
life and death, the basis of the structure is seen to be a mesh- 
work consisting of two substances. One of these is the mesh- 
work itself, the other a ground substance filling the spaces 
between. In addition to these, there are minute, deeply- 
staining granules situated along the branches of the meshwork, 
often quite irregularly, at other times forming regular chains, 
as if the meshwork were entirely composed of them. The 
above three elements may be regarded as constituting the 
active substance of the protoplasm. Besides these, as men- 
tioned before, the protoplasm contains certain passive sub- 
stances, e.g. crystalline bodies, drops of oil, &c. These 
passive bodies lie in the spaces of the meshwork. 
Most of the earlier observers regarded the network as a 
fibrillar substance, forming either a continuous network, or 
consisting of threads simple or branching, and this view is 
sustained by many at the present day. According to this view 
the granules are regarded as nodes in the network seen at the 
points of crossing, or else as actual granules situated in 
the meshwork. 
The more recent observations of Butschli are strongly 
opposed to the above theory. He looks upon protoplasm 
in the light of an emulsion having an alveolar structure. 
Experimenting in support of this theory he has produced 
artificial emulsions bearing a remarkably close resemblance to 
living protoplasm, and has even gone so far as to demonstrate 
that drops of oil emulsion placed in water may show amoeboid 
physical changes. Butschli’s position is the following : 
He maintains that protoplasm consists of drops of a liquid 
alveolar substance, situated in an interalveolar substance of 
a different physical consistency. This interalveolar substance 
forms the walls of the spaces or alveoli in which are situated 
the minute drops of alveolar substance. The so-called net- 
work according to this theory is due to optical section of the 
interalveolar walls. These walls produce the appearance of a 
network, while the spaces of the network are merely optical 
sections of the alveoli. These two theories are called respectively 
