58 THE MICROSCOPICAL NEWS. 
generally agree, is a point to which I wish to call attention, and to 
which I shall have again to refer. The semi-fluid state depends 
apparently on the quantity of water it contains, and protoplasm 
really exists of various consistencies up to the solid ; and, in passing, 
I may just refer to the very great tenacity of life it exhibits in this 
last (solid) state. For instance, some of the rotifers can be dried, 
and after being kept in that state for years will, on being put into 
water, soon regain their original form and vitality and swim about 
merrily, doubtless with a happy unconsciousness of the lapse of 
time since they last so disported themselves. But the most striking 
illustration of this tenacity of life occurs in the vegetable king- 
dom—in seeds, for example—a most notable instance of which is 
mummy wheat, which, after lying by for many centuries, on being 
sown in the ordinary way, grows naturally without any indication of 
loss of power from its long rest. Of course these seeds, as well as 
the dried rotifers, must have retained life through all these years. 
There was no death, but only suspended animation. It is, how- 
ever, in the semi-fluid state of which I have spoken that protoplasm 
can be most readily obtained and best studied. Its chemical com- 
position is said to be very complex, but not to have been exactly 
determined. Its principal elements, however, are oxygen, hydro- 
gen, carbon, and nitrogen. But besides chemical elements there 
is something else which is beyond the range of chemical analysis, 
and that is Life. What Life is we do not know—whether it be 
simply a property of matter, or something different from and higher 
than this. All we know certainly is that it is that which dis- 
tinguishes protoplasm from every other substance, which gives to 
it its peculiar properties, and which enables it to control and 
modify the chemical affinities of the other constituents. Life is 
essential to protoplasm, and it therefore seems to be a mistake to 
speak, as some do, of dead protoplasm. When life has gone it 
ceases to be protoplasm; all we have left being the ordinary chemi- 
cal elements subject to ordinary chemical laws. ‘This, however, is 
a question which it forms no part of my purpose to discuss. I 
simply give my opinion for what it is worth, and will pass on to the 
consideration of the first of the powers of protoplasm to which I 
wish to call attention, viz., the power of assimilation, z.e. of con- 
verting pabulum or food into protoplasm precisely similar to itself— 
non-living into living matter possessing all the powers of the living 
matter which produced it. This may, at the first glance, seem to 
some to be merely a chemical operation, similar to others with 
which we are familiar, in which various substances act and re-act 
upon each other according to certain fixed laws. But there is in 
reality no resemblance between the two ; for I believe that there is 
no instance in which by chemical action any substance, simple or 
compound, converts another substance into one precisely similar 
