Protoplasm by Aid of Microdissection . 279 
membrane. A deep tear in a myxomycete plasmodium will often result in 
the formation of globules of a hyaline substance with characteristic mem- 
branes, and these clear masses of substance are formed not from the 
peripheral hyaloplasm but from granule-free protoplasm which comes from 
the very centre of the plasmodium. Thus, it is apparently the hyaline 
matrix, whether peripheral in location or not, which is capable of forming 
a membrane in myxomycetes. (Whether or not the peripheral hyaloplasm 
of myxomycetes is identical with the matrix of the granular plasma, differ- 
ing only in location, cannot be said, but the two are not as highly differen- 
tiated as are the ectoplasm and endoplasm of Amoeba. In the ciliate 
Etiplotes the differentiation between the two regions is still greater.) 
The capacity for membrane formation persists only as long as the 
protoplasm is normal (although this property of membrane formation is one 
of the last to be lost in dying protoplasm). This fact is well illustrated in 
the behaviour of escaping protoplasm, from a bread-mould hypha or 
a filament of Vaucheria , for example. The first protoplasm which streams 
from a rupture almost invariably forms protective membranes (unless the 
escaping protoplasm be of very high viscosity, as is true of the quiescent 
protoplasm in Rhizopus ). These liquid membranes at first readily increase 
in area as the droplet of escaping protoplasm increases in volume, but later 
they suddenly gelate and rupture from pressure of the inflowing protoplasm. 
The physiological change which has caused the gelation of the membrane 
surrounding the freed protoplasm had also robbed the now degenerate 
escaping protoplasm of the capacity to form a membrane. 
The evidence so far presented favours the belief in a protoplasmic 
surface layer which is usually in the gel state (i. e. firm in consistency). 
This is also Chambers’s contention ( 11 , p. 45). But to Chambers the 
surface layer of so-called 4 naked ’ protoplasm is frequently of ‘ an appreci- 
able depth ’ — that is, the degree of viscosity (of the protoplasmic surface 
layer) is greatest on the outer surface and least on the inner surface. Thus 
does the high consistency at the surface grade insensibly into the very fluid 
condition of the interior. When the surface layer is sub-microscopic, such 
as may form over protoplasm which has freshly come in contact with water, 
then Chambers’s surface film is identical with the protoplasmic membrane as 
I have described it. But when Chambers regards the ectosarc of Amoeba , 
which may attain a thickness of 10 or more micra, as the plasma-membrane, 
I cannot agree with him. On the contrary, I believe that the hyaloplasmic 
border of myxomycetes, the ectosarc of Amoeba , and the surface of all 
so-called e naked ’ protoplasm is possessed of an ordinarily highly viscous 
outer protoplasmic layer of such delicacy as to be immensurable, but which 
does not necessarily grade imperceptibly into the more liquid condition of 
the interior. This outer layer is sometimes so definitely delimited from the 
inner protoplasm as to be optically distinguishable as a definite membrane. 
