184 DR. BEALE, ON CONTRACTILITY. 
and contracted state. It is impossible that a particle could 
move from its position at one or other end of the muscle, for 
instance, and take up a position amongst the particles in 
its central part. Shortening and elongating, thinning and 
thickening, widening and narrowing, relaxing and contract- 
ing, convey an idea of what occurs in the contractile tissue 
of muscle, and each action is a repetition of the last. Al- 
though the actions may differ in degree, still the changes 
which occur in the relative position of the particles are the 
same for every action. 
Now with reference to the mucus-corpuscle, no language 
could convey an idea of the changes which take piace in 
form ; every part of the surface of a corpuscle may be seen to 
change within a few seconds. The material which was in one 
part may move to another part. Not only does the position of 
the component particles alter with respect to one another, but it 
never remains the same. There is no alternation of movement. 
Were it possible to take hundreds of photographs, at the brief- 
est intervals, with the utmost rapidity, no two would be exactly 
alike, nor would they exhibit different gradations of the same 
change, nor is it possible to represent the movements with any 
degree of accuracy by drawings, because the outline 1s chang- 
ing in many parts at the same moment. ‘The varying stages 
of contraction and relaxation of a muscular fibre may be 
represented with great accuracy, because the changes occur 
with regularity, and they are repeated, but it is impossible 
to premise the successive alterations in form of a mass of 
living matter, for it never assumes the same form twice. 
And now to account for these movements,—the component 
particles evidently alter their positions in a most remarkable 
manner. One particle may move in advance of another, or 
round another. <A portion may move info or out of another 
portion. A bulging may occur at one point of the circum- 
ference, or at ten or twenty different pomts at the same 
moment. The moving power evidently resides in every par- 
ticle, of a very transparent, invariably colourless, and struc- 
tureless material. By the very highest powers, only an 
indication of minute spherical particles can be discerned. 
Because “ molecules”’ have been seen in some of the masses of 
moving matter, the motion has been attributed to these. 
It is true the particles do move, but the living transparent 
material in which the molecules are placed moves first, and 
these flow into the extended portion. The movements can- 
not, therefore, be ordinary molecular movements. It has been 
said that the movements may result from diffusion, but what 
diffusion or other movement with which we are acquainted 
