MOVEMENTS OF CELLS. 13 



colourless blood corpuscles, pus corpuscles, and others. On this 

 account it has been doubted whether these movements really 

 depend on the vital properties of the protoplasm. Such move- 

 ments, it may be observed, occur also in dead cells, as in the 

 case of granules that have escaped from cells undergoing disin- 

 tegration, which continue to move, provided that the medium 

 they enter does not present any obstacle. 



Similar movements, too, are found in cells that are clearly 

 living. The dancing movement ceases in the interior of the 

 corpuscles of saliva on the cautious addition of a solution of 

 common salt, containing from J to 1 per cent. ; but this still per- 

 mits the movements of fresh pus or lymph corpuscles to continue. 



Recklinghausen* has described similar phenomena in the 

 latter kind of corpuscles. When the menstruum is diluted 

 with water, they become spherical (an experiment that had 

 already been performed by H. Miiller and Reinhardt),f and the 

 granules in their interior begin to dance ; but as soon as the 

 fluid becomes somewhat more concentrated in consequence of 

 evaporation from the .margins of the cover, this vibratory 

 movement ceases, and the corpuscles commence again to 

 undergo their customary changes in form. 



We see here, then, clearly enough, that two phenomena 

 alternate : if the corpuscles are spherical, the granules dance in 

 their interior ; but if the corpuscles undergo changes of form, 

 then the granules cease to vibrate. It is rare to see the so-called 

 molecular movements in cells which change their shape. It 

 may, however, be occasionally observed in the colourless blood 

 corpuscles of the newt, after the addition of water. The 

 question whether the vibratory movement of the granules 

 stands in relation to the life of the protoplasm is only appli- 

 cable to such living cells. 



Bruckel has referred to the possibility of this connection, in con- 

 sideration of the circumstance that the movements are arrested by 

 induction currents of sufficient intensity. 



* Virchjw's Archiv, Band xxviii. 

 f Virchow's Archiv, Band. i. 



J Veber die sogenannte Molecularen, " On the so-called Molecules," 

 Wiener Sitzungsberichte, 1862. 



