234 
On the BMzopoda. 
[Monthly Microscopical 
Journal, April 1, 1869. 
to the plane on whicli it rests, whereas its upper or free surface 
only is being projected into pseudopodial extensions. In short, 
the ejffect is identical in character with that which would present 
itself if, after filling a transparent and highly elastic bladder — 
as, for example, a bladder formed of extremely thin caoutchouc — 
with some viscid and transparent fluid in which granular particles 
of shghtly greater specific gravity than the fluid itself were 
suspended, we were to roll it slowly along a flat surface. In 
such a case, the upper stratum of granules would in reality be 
moving forwards in the direction in which the bladder was being 
rolled ; whereas the inferior stratum, although at rest, would 
appear to be retrograding; for the same reason that when a 
railway-train is slowly and steadily put in motion, the platform 
appears to be moving from the observer seated in one of the car- 
riages. Now, as regards the cyclosis, this result could not take 
place, if the two phenomena — namely, the vital contractility of 
the protoplasm itself and the circulating force by means of which 
the granules are impelled — acted independently one of the other. 
Did they act independently, any cessation or alteration in the one 
would not necessarily involve a cessation or alteration in the other, 
but the circulation of the granules would continue unchecked even 
when the protoplasmic mass had attained a state of perfect rest. And 
notably, when the direction in which the protoplasmic mass had for 
a time been moving became suddenly reversed, the direction of the 
granular movement would remain unaltered, at least for a period, 
were the force producing it an independent one. But the direction 
which the granules continue to take under these circumstances 
becomes immediately reversed also, proving thereby that it simply 
follows the direction imparted to it by the protoplasm. It only 
remains to be stated that these phenomena are observable whenever 
a fresh pseudopodium is projected ; every modification in the direc- 
tion taken by the current of granules being distinctly referable to 
some corresponding change in the form being assumed by the 
protoplasmic body generally. 
In conclusion, I would observe that although a step or two 
have already been gained in our knowledge of these lower forms of 
animal life, much remains to be achieved before it can with truth 
be said that we have mastered these difficult inquiries. What is 
the precise composition of protoplasm ? What vital functions is it 
capable of performing ? In what does its so-called differentiation 
consist ? Does any recognized difference in the mode of deriving 
nourishment necessarily involve a difference in the atomic consti- 
tution of protoplasm ? And lastly. Can we with any truth be said 
to have as yet arrived at that climax in microscopic analysis at 
which it is safe to assert that our methods and apparatus are 
actually able to enter into competition with the subtlest creations 
