252 DR. DUFFIN, ON PROTOFLASM. 
elucidating the life of the essential cell elements. Unger* 
had been already struck with the close similarity of the 
mobile phenomena of the Polythalamiz with those of the pro- 
cesses of protoplasm stretched across the cavity of many 
vegetable cells. Although he had not personally investigated 
the former, he became convinced, from Schultze’s descrip- 
tion, that a resemblance amounting to identity existed be- 
tween their movements and the protoplasm streams of many 
vegetable cells. Shortly prior to the appearance of Unger’s 
work, Pringsheim,+ in opposition to the theory of the pri- 
mordial utricle then prevalent, insisted that everything that 
lay within the cell-membrane of a living vegetable cell 
might have a complex disposition, but consisted essentially 
of nothing but protoplasma and cell fluid. He admitted that 
in the cortical layer of the protoplasma a distinct arrange- 
ment into layers often occurred, and these he distinguished 
as the cutaneous and granular layers of the protoplasma, but 
he denied that the primordial utricle could be differentiated 
as a membrane from the subjacent protoplasm. If in animal 
cells, partly from their relatively smaller size and partly from 
their greater average wealth in protoplasma, it is more rarely 
possible to make a sharp demarcation between a cortical layer 
of protoplasm and a cell-fiuid, there nevertheless exists a dif- 
ference in the constitution of the former, such that a cutane- 
ous layer, destitute of or scantily supplied with granules, 
encloses the remaining more granular material. The white 
blood-cell may serve as an example. This is, however, very 
different from a proper membrane. 
To pass on to some account of the movements presented 
by the pseudopodia of the Foraminifera. Max Schultze { de- 
scribes them as threads of a transparent material rich in 
granules, presenting a high degree of variability in their shape 
and length. They pursue a diverging course, divide at acute 
angles, and unite to form a kind of network. They are con- 
stantly in motion, lengthening, shortening, subdividing, 
uniting. They are also the seats of an inner activity which 
affects even those fibres that are subject to none of the above- 
named changes. This inner activity is the so-called granule 
movement. It isa gliding, a flowing of the granules contained 
in the substance of the filaments. With a greater or less 
velocity they travel either to the periphery or to the root of 
the thread, often, even in the thinnest threads, in both direc- 
tions simultaneously. When granules happen to meet, they 
* «Anatomie u. Physiologie d. Pflanzeu,’ p. 280, 1855. 
+ ‘Untersuchungen tiber d. Bau u. d. Bildung d. Pflanzenzelle,’ 1854. 
{ ‘Das Protoplasma der Rhizopoden und der Pflanzenzellen’ von Max 
Schulize, 1863. 
