^ 



AN ARTIFICIAL OSMOTIC CELL 51 



REACTIONS OF THE GROWTH TO UNFAVORABLE CONDITIONS 



\\Tien the fragment of KMn04 is dropped into the solution, 

 it is seen that one or more gas-bubbles adhere to it. Microscopic 

 observation reveals the fact that a gas-bubble always appears 

 in the situation where a stem is about to sprout forth (see fig. 

 3, A). Not infrequently it happens that this gas-bubble is 

 caught in the open tip of the stem (see fig. 3, Bl). Growth takes 

 place around the gas-bubble, the stem showing a protuberance 

 in that point, the wall of which is sometimes thinned out so that 

 the bubble can be plainly seen through it (see fig. 3, B2). If 

 sufficient space is left between the inner wall of the stem and 

 gas-bubble for the free onward-flow of the solution within, no 

 other reaction occurs (see fig. 3, B4). If the space is too nar- 

 row, a branch shoots out from the stem (see fig. 3, B3). 



At a temperature of about 56°C. the fluid within the tip of 

 the stem coagulates. The pressure within the stem forces out 

 this coagulum, which appears in the form of a fine, convoluted 

 thread about the upper part of the stem. The increased pres- 

 sure within the stem, however, soon causes the outgrowth of 

 branches. The coagulation of the fluid within the tips of these 

 branches results in the outgi'owth (from the branches) of finer 

 branches. The finer branches, in their turn send out still finer 

 branches, until the growth appears like a thick mass of matted 

 threads (see fig. 3, C). 



When a stem is entirely broken off, a new conical tip rapidly 

 forms upon the stump and growth proceeds as before. Advan- 

 tage was taken of this fact to obtain successive crops of stems 

 without replanting the crystals, until the osmotic sacs were 

 exhausted of the contained KMn04. A somewhat modified 

 reaction occurs when the stem is broken so as to retain the broken 

 part on a line with the stump. The latter may be accomplished 

 in the following manner: Stems are grown upon glass slides, 

 as directed above. When grown to some length, they are cut 

 across with a knife and the slides again immersed in the solu- 

 tion, as far as possible in the same situation as before. A few 

 minutes after the cut stems have been immersed, it is found 



