AN ARTIFICIAL OSMOTIC CELL 39 



vagueness that remains evident in these circles, about osmotic 

 phenomena, for instance — seems to render some acquaintance 

 with the plant-Uke and animal-like growths of precipitation 

 cells almost a prerequisite for constructive research in proto- 

 plasmic physiolog^^ If the phenomena of cell growth in organ- 

 isms are ever to be stated in physical and chemical terms, the 

 principles to be worked out for artificial growths will surely be 

 of great value in the formulation of such a statement. 



The osmotic growths hitherto studied^ have been of the form 

 of closed tubes or cells, open to the outside only momentarily 

 (as in the case of Traube's ferrocyanide cell), and their walls 

 have been soft and unstable. They have been irregular in 

 form, bending or breaking at points impossible to foresee; and 

 it has beea almost impossible to regulate the direction of growth 

 and the production of branches, so as to make them capable 

 of careful study. The osmotic growth about to be described is 

 offered as a modification of those hitherto produced, which lends 

 itself easily to regulation and to study. The tubes are of firm 

 and stable composition, so much so, that specimens have been 

 kept for eighteen months without change, and there is no reason 

 to think that they may not be kept much longer. They are 

 always open at the growing end and are filled with a watery 

 solution. The diameter of the tube is nearly uniform through- 

 out, and the direction of growth may easily be controlled by defi- 

 nite conditions in the surroundings. Except under certain defi- 

 nite conditions no branches are produced, but they may be pro- 

 duced at will. Unlike the growths hitherto studied, these may 

 be grown to a great height, specimens nearly 2 meters high hav- 

 ing 'been produced with ease; the limit of growth in these experi- 

 ments is only the height of the available vessel. They are 

 extremely sensitive to many variations in their surroundings 

 and react to them promptly and definitely. 



3 Bottger, R., Ueber Erzeugung Baum-und strauchartiger Vegetationen. 

 Jour. Prak. Chem. 101: 295-296. 1867. 



Quincke, G., Ueber unsichtbare Fliissigkeitsschichten und die Oberflachen- 

 spannung fliissiger Niederschlage bei Niederschlagsmembranen, Zellen, CoUoiden 

 und Gallerten. Annal. Physik. 7: 589-631, 701-744. 1902. 



