16 PROTOPLASMIC CIRCULATION. [CH. I 



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

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

 Both sets of seeds should now be sown in damp sawdust, 

 the lot (b) having been previously soaked in cold water 

 for twelve hours : it will be found that lot (6) 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 Droserct 

 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-rib 1 , 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 



1 Or at the edges of the leaf. To start circulation the leaves should 

 be cut an hour before they are wanted. Or it may be necessary to warm 

 the preparation for a few minutes. 



