AN ARTIFICIAL OSMOTIC CELL 



53 



fig. 3, D). The old canal is on a line with the stump, the new 

 somewhat to the side. Further growth is along the line of 

 the latter canal. 



When the medium is too thin, the osmotic pressure within 

 the stem forces the KMn04 solution through the wall of the 

 stem, with the result that the latter becomes surrounded by a 

 brownish precipitate. Growth under these conditions is tardy, 

 the stems remaining stunted. 



MUTUAL INTERFERENCE 



A number of osmotic growths crowded together in a limited 

 space, affect each other's growth in several interesting ways. 

 To elucidate the facts in this connection, a series of experiments 

 was carried out, as follows: Various numbers of fragments of 

 KMn04 (as nearly as possible of the same size) were planted 

 in test tubes (also of the same size), filled with the solution to 

 the same height, and placed as far as possible under the same 

 conditions of temperature, etc. After a certain number of hours 

 the solution in the test tubes was replaced by water and the 

 stems grown were counted and measured (through the glass). 

 Following are two typical tables of the results obtained. 



TABLE 1 



Stems were permitted to grow for eight hours in six test tubes, each 20 cm. in height 

 and 1.5 cm. in diameter, with the following results 



THE PL.\NT WORLD, VOL. 20, NO. 



