12 PROTOPLASMIC CIRCULATION. [CH. I 



test-tubes are corked and are immersed in a beaker of 

 water kept by means of thermostat at 60° 0. for 2 hours. 

 Both sets of seeds should now be sown in damp saw-dust, 

 —the lot (6) having been previously soaked in cold water 

 for twelve hours : it will be found that lot (b) germinate, 

 while (a) do not do so, and show other obvious signs of 

 being dead. 



(16) Circulation of Protoplasm — Sachs' Hot-Box. 



Any parts of plants, in which circulating protoplasm 

 can be observed, serve as material for studying the effects 

 of temperature. The staminal hairs of Tradescantia, or 

 other plant-hairs are convenient, or the tentacles of Drosera 

 may be used. But the leaves of Elodea are perhaps most 

 easily obtainable throughout the year. 



Mount a leaf of Elodea upside down in a drop of water 

 under a large cover-glass ; look for circulating protoplasm 

 near the mid-ribS and subject it to gradually increasing 

 temperature by means of any of the recognised "hot- 

 stages," e.g. with Sachs' Hot-box. The arrangement is 

 described and figured in Sachs' Text Book, English Trans- 

 lation, p. 736. It consists of a hollow-walled metal-box, 

 into which the microscope is placed so that by filling the 

 walls with warm water the object under observation can 

 be subjected to the desired temperature. A window 

 admits light, and a hole in the moveable lid allows the 

 microscope-tube and fine adjustment to project. The 

 felt lining of the lid should be wetted and a little water 



1 The leaves should be cut off an hour before they are wanted, 

 because, in winter at any rate, circulation is not visible until some time 

 after the leaves have been cut. 



