THE LIVING SUBSTANCE. 29 



At one moment the substance becomes a film so tenuous as 

 almost and then quite to elude the most careful search, yet 

 having a true structure of Biitschli ; then gathers itself up 

 into blunt pseudopodia of great thickness, and of double, or 

 triple, or manifold, alveolar differentiation ; then spins itself 

 out into long delicate whip-lashes, which are at first coarsely- 

 structured near their bases, but pass into invisibly subdivided 

 states, and become so viscid as to bend under mechanical 

 pressure of the cover-glass, like a stiff bristle as they extend 

 straight out in the water. The tip of these rays may elongate 

 still further till a fine thread forms. Before, or after, this last 

 change they are optically so refractive that they glitter, and 

 have a greenish hue like glass rods. 



In pseudopodia so modified, are seen contractile activities ; 

 for they bend about like tactile organs, as, indeed, they prove 

 themselves in various ways to be for the time. At other 

 moments they bend their length into contorted spirals and 

 ram's-horn-like shapes, and then again, lengthening, will lash 

 the water about in a frenzied way exactly like overgrown cilia 

 or flagella. 



A momentary touch upon the cover-glass will in one moment 

 convert all of this display into inactivity, leaving but a shape- 

 less lump of slightly amoeboid protoplasm, which usually sinks 

 more or less in the water. That area in the mass from 

 whence arose the contractile processes is different for a few 

 moments, has a more uneven and disturbed appearance than 

 the rest of the lump. And when the creature resumes its 

 activities, it is from this same area that there usually arise 

 again new organs having the same peculiar characters and 

 showing the same metamorphoses and activities ; while those 

 portions whose processes were more ordinary pseudopodia again 

 produce these ; showing that the activities, though intermitted, 

 were only suspended, and that their suspension was a phenom- 

 enon physiological, and not of physical control alone. 



It must be remembered that the slight jar to the cover- 

 glass was only one of countless vibration disturbances to which 

 the animal is subjected ; of a different character from those 

 occasioned by passing organisms, but still only a jar, which 



