262 DR. DUFFIN, ON PROTOPLASM. 
cludes, under the term “‘ formed material,’ not only all mem- 
branes and intercellular substance, but also those various 
precipitates, as starch, oil, &c., that may come to occupy the 
interior of the cell. His “‘ germinal matter” seems to corre- 
spond generally with Schultze’s definition of protoplasm. It 
is the sole seat of those movements that have been described. 
Both Schultze and Briicke are much troubled how to regard 
either the origin or the function of the nucleus. The latter 
even says* “the constancy of its appearance is subject to 
essential limitations if, as cannot be avoided, the cells of Cryp- 
togams are also considered, and it be not assumed that 
the nucleus must be present even where it is invisible.” 
Schultze, on the other hand, includes the nucleus in his 
definition of a cell. Neither tells us in what light to regard 
the nucleolus when it exists, and we often find, particularly 
in the vegetable kingdom, that the protoplasm itself would 
admit a further separation of parts. If we understand Beale 
aright, the difference between nucleolus, nucleus, and pro- 
toplasm, is only one of degree, the former being younger and 
more “ vitally” active “ germinal matter” than the latter, but 
all presenting this important contrast to all formed material, 
that under the influence of an appropriate pabulum, they are 
capable of indefinite multiplication. Beale therefore regards 
all living structures as consisting of matter in two essentially 
different states, that which és living and that which has lived, 
and the first passes into the last, the transition bemg some- 
times so gradual that, by the action of carmine, many zones 
may be demonstrated, the outer not being coloured at all, 
while the inner ones are very intensely coloured.t That in 
order to find the most active centres we must even look for 
particles, far smaller than the nucleolus, is most probable. 
It is as difficult to conceive an ultimate living centre as to 
conceive the universality of space. The formed material, 
on the other hand, whether in the shape of cell-membrane or 
intercellular substance, is practically but the altered germinal 
matter, and although endowed with most important func- 
tions, restricts the growth of the germinal matter within cer- 
tain limits, and it cannot, like germinal matter, produce new 
matter like itself. All pabulum must pass through the formed 
material before it can reach the germinal matter within, and 
therefore it follows that the rate of growth of the germinal 
matter is determined by the permeability of the formed mate- 
rial. He thus explains alterations in the rate of growth 
* “Die Elementar-organismen,’ op. cit. 
+ ‘The Structure of the Tissues ;’ see also a paper in the ‘Archives of 
Medicine,’ vol. ii. 
