ARCHER, ON STEPHANOSPH ERA PLUVIALIS. 195 
It may be asked, where is the rolling, onward flow of the 
granular contents in the Mesotznium alluded to, and here, so 
characteristic and conspicuous in my amceboid bodies, and 
requisite to carry out the analogy? I believe the flowing 
movement of the contents in the latter is due to its granular 
condition; the granules, free and distinct from each other, 
are urged on by the contractile power of the bounding proto- 
plasmic mass; they therefore naturally assume a flowing 
movement, to a certain extent resembling that of the blood- 
discs in the vessels of the higher animals. In the latter 
instances, on the other hand, the contents have not become 
all so finely and freely disintegrated, and the whole con- 
tents are simply compressed and so moulded by the 
contractile power of the bounding protoplasmic mass as to 
become adapted to pass through a comparatively narrow 
outlet. In. both instances the solid contents seem to be 
passive, and are urged along by the contractile power of 
the external protoplasmic mass. In the one instance, the 
contents, loosely granular, are powerfully and rapidly acted 
upon by momentary and even fitful changes of the lobose 
expansions and the contractile efforts of the protoplasmic 
mass, and the granules flow. Jn the other the contents, still 
maintaining a coherence and much of their original disposi- 
tion, are slowly (but surely) acted upon by the gradual, and 
except at intervals imperceptible, but not less actual, con- 
tractile power of the protoplasmic mass, and they are thereby 
carried with it. Even in the latter instance there does exist 
a certain amount of the same kind of movement of the solid 
contents as in the former; but as the whole process is so 
greatly slower, and the contractile force comparatively so 
much less energetic, it is not so perceptible. In my mind the 
analogy is exact—the difference is in degree. 
Now, let us for a moment imagine an Amaba princeps or 
diffluens imprisoned within such a rigid cyst as that of the 
parent-membrane of my Mesotenium mirificum, or within 
the cavity of a joint of a Spirogyra, and with only one nar- 
row aperture, considerably smaller than itself by which it 
could possibly get free. Now, further, let us suppose our 
Ameba acted upon by the impulse to get out,—there can be 
no doubt but that it could perform the feat—and its modus 
operandi, so far as I see, would not essentially differ from 
that of the true vegetable cell, in actually effecting the same 
object inthe course of its own natural developmental vital 
processes. 
Starting, then, from such cases, and passing on through 
the more decidedly reptant amceboid bodies of Rhizidium, of 
