4 BOTANICAL MICROTECHNIQUE. 



2.) The escape is provided for in the same way by a linen 

 strip (S lt ) which communicates with the small beaker (B tl ). 

 The rate of flow can, obviously, be regulated by changing 

 the height of the water in the beaker B v , as well as by fill- 

 ing the siphon H more or less tightly with linen. J. af 



FIG. 3. Part of a microscope with apparatus for culture in flowing water. After 

 J. af Klercker. 



Klercker commonly allows a flow of about 50 ccm. in 24 

 hours. 



4. In order to protect long-continued cultures of Algae 

 from Bacteria and other fungi, one may, with Klebs (III, 

 492), add to the culture fluid .05% of neutral potassium 

 chromate (K,CrO 4 ), which does no perceptible injury to 

 Algae or to sections of higher plants. Palla (I, 322) 

 added for the same purpose .01% of potassium bichromate 

 (K 2 Cr,0 7 ). 



5. If one wishes to observe sections of larger plant-tissues 

 in the living condition, they must, naturally, be always more 

 than a single cell-layer in thickness, so that they may con- 

 tain cells in no way injured by cutting. Most cells, how- 

 ever, die pretty quickly in pure water, when the chromato- 

 phores and the nucleus often become completely deformed 

 by swelling strongly. 



Therefore very various fluids have been used for the study 

 of living cells, such as solutions of neutral salts, 2 to 10 per 

 cent solutions of sugar, gum arabic, and fresh egg-albumen. 

 In the study of nuclear divisions in the embryo-sac, a 



