278 Seifriz . — Observations on some Physical Properties of 
tough. Fragments of it can be dragged into the plasma mass. (This is, of 
course, the gelated, degenerate membrane. The living membrane cannot 
be separated from the protoplasmic mass.) 
The highly viscous, inactive protoplasm from the hyphae of the 
bread-mould Rhizopus , when exposed by a rupture or when forcibly 
ejected through a tear in the filament of the mould, forms no membrane. 
Its high gel consistency is apparently not conducive to membrane formation. 
That protoplasm of gel consistency is incapable of forming a membrane is 
not surprising, since a not too high viscosity is a physical prerequisite 
to a readjustment of particles. On the other hand, very dilute protoplasm 
does not always form droplets, with apparent membranes, when freed. 
This truth is well illustrated in the behaviour of the protoplasm of 
Amoeba . The ectoplasm of Amoeba , though very viscous, will invariably, 
if normal, round up into small spheres when bits of it are isolated, while 
the endoplasm which is of low viscosity does not round up when 
freed nor form a protective surface, but mixes with the surrounding 
medium. 
This behaviour suggests the view of de Vries that the plasma- 
membrane is formed only from the ectoplasm. De Vries looked upon 
the hyaloplasmic border of myxomycetes and Amoeba as the ‘ organ of 
cell membrane formation ’. That the plasma-membrane is made from 
hyaloplasm (matrix) and not granular protoplasm is evident from the fact 
that it is hyaline and possesses no granules. That it is usually formed from 
the hyaloplasmic border of myxomycetes and the ectosarc of Amoeba 
is likewise very evident in view of the fact that these regions are external to 
the internal granular plasma and therefore are the first to come in contact 
with the surrounding medium when the surface is torn. But that the ecto- 
plasm is the ‘ organ ’ of membrane formation is not without experimental 
disproof. 
It is generally true that a rupture in the surface of Amoeba which 
leaves ectoplasm exposed is quickly covered over without much if any loss 
of protoplasm, and, further, small globules of ectoplasm pinched off readily 
round up and maintain their identity, although their viscosity is consider- 
ably higher than that of the endoplasm. The endoplasm, on the other 
hand, when exposed to the surrounding medium by a deep wound, usually 
flows out and mixes in the medium, and apparently never forms a protective 
membrane unless a surface layer of ectoplasm is first established. I have, 
however, observed so rapid a transformation of the freshly exposed surface 
of liquid endoplasm that granules are caught in the membranous gel. What 
usually takes place when an Amoeba is torn by a deep rupture and the liquid 
endoplasm is not lost by dispersion is, apparently, a rapid conversion of the 
peripheral granular plasma into a more viscous granule-free layer, the ecto- 
sarc, which, in turn, at its surface is converted into the highly viscous 
