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cause of motion cannot be osmotic, because the reagent which at 

 once stops the motion from place to place, increases the action of 

 the osmotic force. Second, that the fact of phismolysls occurring 

 only after a certain strength of solution is used proves the exis- 

 tence of a turgor pressure, which^ reckoned according to de Vries, 



equals that of from four to five atmospheres. Therefore, if pores 

 exist with inner openings in contact with the contents, the pres- 

 sure within must cause the forcing out of a part of these contents 

 sufficient in quantity to account for the motion of the diatom. 



He speaks here of the question whether the motion is a free 

 swimming one, that is, independent of the position of the cell, or 

 as some claim, a creeping one, such that a certain position of the 

 cell in relation to some fixed substance must be maintained. He 

 says the first kind of motion may easily be proven, but that this 

 does not preclude the possibility of the latter. The greater num- 

 ber of species examined by him live in slimy water where they 

 can easily find fixed substances, but even in the so-called creep- 

 ing motion there was nothing amoeba-like to be discovered. 



In connection wath the use of certain reagents producing a 

 plasraolytic condition, a very rapid increase in oil was noticed m 

 the contents of the cell. This increase also occurs in cultures 

 which are becoming old, but here the process is much slower. 

 He conjectures from this fact that the rotation of the protoplasm 

 on the surface of the wall maybe the means by which the plant 

 gets its necessary supply of oxygen. He give this, however, 

 merely as a hypothesis which requires further experiments. 



E. L. G. 



The Walls of subcrous Cells, — In a recent number of the " Bot- 

 anisches Centralblatt " is a short review of a long article by C. von 

 Wisselingh on the walls of the suberous cells. This article appeared 

 some months ago in the Archives Neerlandaises, in which the 

 author gives the results of a long series of chemical tests as to the 

 nature of the substance known as suberin. The author claims 

 that in membranes containing suberin, wax is of much more fre- 

 quent occurrence than has hitherto been supposed. On the other 

 hand, the suberous lamelte contain no cellulose whatever, and, in 

 this respect, differ from the cuticularized layers. This is in direct 



