LIVERPOOL MICRO. SOCIETY.—PRESIDENT’S ADDRESS. 63 
of contraction and expansion of this slender thread of protoplasm ; 
for remember, these organisms are simple cells so far as we can see. 
The simplicity of structure of these infusoria is shown in many 
ways : for instance, by the beautiful Paramecium, Bursaria, in which 
the cyclosis of the protoplasm may be seen very much as in the 
leaf cells of valisneria and some other plants. And thus we have 
another instance, in the movements of cilia and flagella, of an 
effect being produced without any visible adequate means. 
We will now leave this, and consider the power of construction 
possessed by protoplasm, which, embracing as it does all things 
living, both animal and vegetable, is much too large a subject to be 
taken in its entirety ; so with respect to the greater part of it we may 
content ourselves with the fact that all living forms from the amceba to 
man, and from the tiniest fungus to the stateliest forest tree, are 
built up by the direct or indirect action of protoplasm: all arise 
from that primitive cell of which the amceba is the type. I would 
rather now call your attention to the structures or homes which 
protoplasm, in its simplest forms, makes for itself. Among 
them are those of the Diflugia proteiformis, and similar low 
organisms. They are simply somewhat irregular, round, or egg- 
shaped cells of a hyaline film, or foundation covered with frag- 
ments of earthy and other matters, which have probably been 
picked up in the neighbourhood. At one end is an opening 
through which the occupant (which seems to be an amceba with a 
taste for housekeeping) pushes out pseudopodia in search of food, 
or for purposes of locomotion. The Arcella, an equally structure- 
less creature, constructs a neater habitation, in fact a really pretty 
one, generally of a rich brown colour, and dotted, or reticulated 
like a diatom, much the same shape as a Tam o’ Shanter hat, and 
with an opening similarly placed to that in the hat, through 
which the occupant thrusts its pseudopodia, and so communicates 
with the world. I might go on with other illustrations of gradually 
increasing complexity, not forgetting the elegant tubes and vases 
constructed by some of the flagellated infusoria, but will pass on, 
with this simple reference to them, to those beautiful objects, the 
diatoms of the vegetable and the polycistina of the animal world. 
In diatoms we find minute specks of endochrome (the active 
living part of which is protoplasm) enclosed in silicious cells of 
the most varied shapes—sigmoid, circular, triangular, square, &c., 
of great delicacy, and many of them ornamented with regular and 
beautiful patterns in lines and dots—dots or beads principally— 
high powers frequently resolving into beads the lines shown by 
lower ones. 
Some of the circular diatoms, such as Arachnoidiscus and 
-Heliopelta, are extremely beautiful: the former especially is sug- 
gestive of a fine circular window. Diatoms increase in the same 
