280 Seifriz. — Observations on some Physical Properties of 
Though this is with difficulty seen in the living condition, it is often readily 
to be seen in degenerate protoplasm . 1 
The Degenerate Membrane . The observations so far presented have 
had to do almost entirely with the living plasma-membrane. Although 
the evidence for the presence of an outer more viscous protoplasmic layer 
seems to me to be conclusive, it must be admitted that this layer cannot be 
irrefutably demonstrated to be, in the living state, a definite membrane quite 
distinct from the protoplasmic mass which it bounds. The structure is such 
a delicate one, and is, after all, so little different from the inner protoplasm 
itself (of which it is when liquid so intimate a part), that separation of the 
living membrane by dissection is a physical impossibility. 
The reactionary attitude of our science to observations on dead 
material is a healthy one. The criticisms directed against any evidence 
which purports to prove the existence of a living membrane by the 
presence of a dead one are legitimate. For example, the dead structure 
may be an entirely new product — perhaps a precipitation is formed as 
a result of death. That this is a possibility, I grant. But the dead mem- 
brane is to all appearances so evidently a structure having the same position 
and dimensions as that which can sometimes be observed on living proto- 
plasm, that it is worthy of some consideration as evidence of the existence 
of a membrane about the living substance. 
If the escaped protoplasm from a pollen tube, of Iris e. g., is allowed 
to gel — that is, to degenerate — the membrane formed at the time of ejection 
becomes fixed (possibly coagulates). It can then sometimes be isolated 
from the protoplasmic mass and dragged about as one would handle a film 
of scum such as forms on boiled milk. 
In a myxomycete plasmodium one frequently finds large globular 
masses that are quite distinct from the larger protoplasmic mass in which 
they rest. The protoplasm which they contain is, so far as can be deter- 
mined, identical with that of the plasmodium proper. These globules can 
be isolated and torn open, and when partly emptied they are found to 
be sacs bounded by a delicate membrane which on dissection is found to be 
a tough rigid gel. Before isolation, when the globule is handled while still 
within the plasmodium, the membrane is soft and exceedingly sensitive, 
often breaking before a perceptible indentation can be made. The change 
from this state to that of the isolated membrane is the result of degeneration 
and gelation. 
1 Sharp delimitations between protoplasmic regions are common enough in organisms. That 
such structures as the nucleus, chromatophores, &c., are sharply delimited from the surrounding 
protoplasm is evident, but even less specialized regions such as the ectoplasm may be sharply 
delimited from the rest of the protoplasm. Of the ectoplasm of Euplotes, Taylor (42) says, 
‘Frequently, there is evident a fairly definite boundary between the ectoplasm and endoplasm, but 
this condition apparently varies. If (upon disintegration) its outflow be not too rapid, the endoplasm 
separates from the ectoplasm . . . ’ 
