408 Prof. Reichert on the Phenomena of Motion 



mentj but also cause the optical expression of the granular 

 movement. Therefore body-substance with globules could not 

 have flowed to the rays : the fallacy was evident. 



The question now was to trace accurately the apparent grain, 

 the true form of which could not be judged of during motion, 

 at the moment of its formation and disappearance. For this 

 there are plenty of opportunities. The shell certainly prevents 

 the observation of many granules ; we cannot say how the appa- 

 rent granules are produced and lose themselves there ; but we 

 cannot assert that they there flow out of or into the substance 

 of the body of the animal. With some attention, however, it is 

 very soon discovered that both the centripetal and centrifugal 

 movement of the granule may commence and terminate at any 

 part of the extended filaments outside the shell. Here the fol- 

 lowing observations may be made during the appearance of the 

 granule, which has hitherto been considered only in motion. On 

 any spot of the hyaline extended filament, there appears sud- 

 denly an apparent thickening of fusiform outline, of somewhat 

 yellowish colour and dark, contour ; the apices of the spindle 

 lose themselves quite imperceptibly in the neighbouring parts 

 of the filament which have remained unaltered. Soon after- 

 wards it appears as if the spindle became shorter, but thicker 

 and darker in the middle, where it projects more beyond the 

 level of the filament ; finally, the extremities of the apparently 

 fusiform thickening disappear from the view, and the elevated 

 central part jumps along upon the surface of the filament in the 

 likeness of a granule. On the cessation of the movement, the 

 granule disappears in exactly the same manner, but in a reversed 

 order. 



Any one who has traced the gradual production and cessation 

 of the granular movement will assuredly give up the notion of a 

 truly flowing substance in the pseudopodia — a notion which has 

 been derived from an erroneous transference of the phenomena 

 of contraction visible in the Amoeba to the pseudopodia of the 

 Polythalamia. In these we have evidently extended contractile 

 organs of the Polythalamion, in which no cavity and no true 

 granule, either in or upon it, is to be detected ; and the pheno- 

 mena described in connexion with the granular movement there- 

 fore require that the latter, as already hinted at by J. Muller, 

 should be interpreted as a phenomenon of contraction. Our 

 knowledge of visible phenomena of contraction is limited, as 

 already mentioned, to the changes of form occurring in the con- 

 tractile organs in consequence of invisible movements in the 

 contractile substance itself; and even in this respect the scanty 

 observations upon their structure and texture still leave much 

 to be desired. In the present case, only the contraction-wave 



