34 THE AEEANGEMENT OF THE 



Analysis of Rest. Living matter, as long as it is alive, can never 

 be at absolute rest, and in the protoplasm a uniform distribution 

 of the reticulum is not observable as long as motion is present. 

 The condition of comparative rest (Fig. 2) may be exhibited by a 

 portion of the protoplasm while another portion is in the con- 

 dition of contraction, another again is in that of extension. Rest 

 is death, and seen in motionless blood or pus corpuscles, which 

 on dying often assume the globular shape viz., an accomplished 

 equilibrium of the reticulum. By evaporation of the liquid, even 

 such globular bodies may present a jagged, irregular shape, 

 which is not amoeboid, as erroneously has been asserted, but the 

 result of shrinkage. Death, however, may ensue at any moment 

 during contraction or extension, if the living matter be killed 

 instantaneously by a re-agent. Motionless pus-corpuscles f. i., 

 in urine may be found in greatly varying amoeboid shapes, and 

 the peculiarities of the reticulum in the contracted and extended 

 condition remain fixed in such corpuscles if kept in preserving 

 fluids f. i., solution of chromic acid. 



Analysis of Contraction and Extension. Contraction of the 

 reticulum causes the amoeboid motion and the locomotion of a 

 protoplasmic mass. The liquid held in the meshes, being driven 

 out of the contracted portion, will rush into a portion at the time 

 at rest, and will extend this portion in the shape of what has 

 been termed pseudopodia. If contraction takes place in one half 

 of the protoplasmic mass, the other half will be in extension ; if 

 two peripheral segments be contracted, the intermediate portion 

 will be extended. The latter was wiggested by Hermann/ long 

 before the structure of protoplasm was known. In the former 

 instance a flap will protrude, nearly of the diameter of the body 

 itself j in the latter a narrow offshoot, a " pseudopodium," will 

 make its appearance, varying in length, and exhibiting either an 

 indistinct structure or being apparently devoid of structure, on 

 account of the great stretching of the reticulum. To allow loco- 

 motion to be accomplished, the protruded flap must adhere to a 

 solid base, so as to have a point of fixation, toward which the 

 balance of the body is dragged. An amoeba, a colorless blood- 

 corpuscle, can commence creeping only after one of the protruded 

 flaps has reached the upper surface of the slide or the lower 

 surface of the covering-glass, for the same reason that a man 

 can make a step only on a solid ground, and climb only by 

 attaching himself with arms or legs to a support. The motion 

 of protoplasmic lumps is liveliest if the slide and cover be close 



