Physiology of the Muscles. 487 



the attracted substance to themselves. If the amber be not rubbed, or 

 the steel bar otherwise magnetized, they are "dead" to such power. 

 The movement of a free body to a magnet has always excited interest, 

 often wonder, from its analogy to the self motion so common and ap- 

 parently peculiar to life. ... A speck of protogenal jelly or of sarcode, 

 if alive, shows analogous relations to certain substances, but the soft 

 yielding tissue allows the part next the attractive matter to move thereto, 

 and then by retraction, to draw such matter into the sarcodal mass, 

 which overspreads, dissolves and assimilates it. 



We say that the Protogenes, or Amoeba, has extended a "pseudopod, " 

 has seized its prey, has drawn it in, swallowed and digested it. No ' 'or- 

 gans, " however, are recognizable ; neither muscle, mouth nor stomach. 

 ' ' If the portion of iron attracted by the magnet, became blended with 

 the substance of its attractor, the analogy thereto of the act of the 

 amo3ba would be perhaps closer, more just than that other analogy 

 which is expressed by terms borrowed from the procedure of higher or- 

 ganisms. " 



When protoplasm is subjected to the influence of a galvanic current, 

 it contracts as a lead wire does ; that is, the energy of the current dis- 

 poses its atoms after that fashion. Not that the protoplasm does any- 

 thing, any more than mud does when struck with a stone. It would be 

 just as correct to say that mud indents when struck, as it is to say that 

 protoplasm contracts, still there is no harm in using the term with the 

 understanding and reservation here pointed out. Contractility, then, is 

 a property of protoplasm, and we see it in action in the Amo3ba, the 

 white blood corpuscle, and all the forms of the most simple protoplastic 

 organization. Probably the very first differentiations are those which 

 relate to this quality of contractility, and consist in the rendering of 

 certain parts, through habit of use, more contractile than other parts. 

 The Amoebae push out and draw in first one part and then another, ap- 

 parently with little or no choice of part, one being about as contractile 

 as another. But in the Actinophrys and in the Foraminifera the parts 

 used, the pseudopodia, are more or less constantly the same. They 

 have acquired greater facility and are more rapid and more varied ifi 

 their movements. Around the mouth of the Vorticelli, and other infu- 

 soria, there is a row of vibratile cilia. These consist of hair-like pro- 

 cesses which, by their constant motion, create a current of water flow- 

 ing into the mouth and carrying with it particles of matter. Such of 

 these particles as are suitable food for the animal are absorbed and the 

 rest rejected. Others of these low organisms, as, for example, the 

 spores of the microscopical Algae, &c. , possess cilia on their outer sur- 

 faces by the vibrations of which they are caused to rotate in the water 

 and to move about. Still others are furnished with one or more long 



