260 DR. DUFFIN, ON PROTOPLASM. 
into harmony with those of other contractile bodies is obvi- 
ously very great. The former is evidently associated with a 
change of locality, not only of the granules but of their im- 
mediate neighbourhood, for it is only possible thus to interpret 
the arrival of the substance of the pseudopodia at places that 
it did not previously occupy, and the complex changes im the 
arrangement of the protoplasma. This Briicke also admits 
for the hairs of Urtica urens, but he distinguishes two kinds 
of movement in their protoplasm ; a slow, creeping or draw- 
ing movement, upon which the changes in the arrangement 
of the protoplasm depend, and a more rapid flowing which is 
observed in the movements of the numerous granules. Whilst 
the former is directly referable to contraction of the proto- 
plasm, the latter depends upon a granular fluid enclosed by 
the contractile plasma, and from which it derives its move- 
ment. Thus, Briicke would draw a distinction between the 
cortical and medullary portion of the protoplasma. As the 
movement of the granules can be accounted for in the same 
manner as those of the pseudopodia of the Polythalamiz, 
Schultze sees no reason for admitting this differentiation. 
Before closing this analysis we would make a few remarks 
upon the fresh light thrown by these observations on the move- 
ment of granules generally. Beale* describes the mucus- 
corpuscles as ‘‘composed of soft semi-transparent matter 
which exhibits delicate spherical particles, varying in size in 
every part. These particles are in constant motion. Ina 
few moments an oscillation of the particles is observed at 
some portion of the circumference of the mass. ‘Then one 
or more bulgings occur, and parts of the surface become 
quite uneven by the formation of a number of little processes 
which move from the general mass and often assume the 
form of little spherules, which still remain attached by narrow 
pedicles to the general mass. Occasionally two or more 
processes coalesce, and a ring may be momentarily produced 
at some part of the circumference. From the first protrusions 
smaller protrusions very often occur, and these gradually 
become spherical, but remain attached by a narrow stem, and 
in a few seconds, perhaps, again become absorbed into the 
general mass.” The different forms assumed by the same 
mucus particle during one minute are represented in Pl. IX, 
fig. 15, in Vol. XI of the ‘Transactions of the Microscopical 
Society.’ Beale further states that the transparent moving 
matter is itself composed of very minute, spherical particles, 
and describes the movements of the larger spherical particles 
which make their way from the general mass into the new 
* ¢ British Medical Journal,’ Nos. 115—117, 1863. 
