PRACTICAL WORK 89 



and in some of the lower multicellular animals, by the 

 separation of parts of the body which are not special 

 reproductive cells, e.g. by the separation of some 

 segments of the body in worms or by the rooting of 

 cuttings and " layers " of plants. This formation of 

 new individuals from non-specialised or only slightly 

 specialised parts of the ordinary body of the organism 

 is called vegetative reproduction. It does not occur in 

 the highest animals. 



PRACTICAL WORK. 



A. RESPIRATION AND PRODUCTION OF HEAT IN LIVING SEEDS 

 AND FLOWER BUDS. 



(1) The test tube provided contains living barley grains 

 (seeds) which have been wetted and placed in the test tube, 

 which was corked on the previous day. They absorb water and 

 swell as a preliminary to sprouting. They also absorb oxygen 

 and give off carbon dioxide in considerable quantity as a result 

 of the rapid respiration of their living cells, which resume active 

 life as a result of absorption of water and oxygen. Test for 

 the carbon dioxide by dipping the rod into lime water, carefully 

 uncorking the test tube and inserting the tip of the rod close to 

 the grains without touching them. After thirty seconds or so look 

 at the drop of lime water on the rod against a dark background. 



(2) Examine the demonstration consisting of a U-tube con- 

 taining coloured water and connecting with two corked flasks, 

 one containing wetted living and the other wetted dead barley 

 grains. Fixed to the cork inside each flask is a lump of caustic 

 potash which readily absorbs carbon dioxide. In the flask con- 

 taining living grains oxygen has been absorbed by the grains 

 while the corresponding carbon dioxide produced is absorbed 

 by the caustic potash. In the flask containing dead grains no 

 such change has occurred. Hence the total amount of free 

 gas in the two flasks changes and the pressure on the surface 

 of the liquid in the two limbs of the U-tube becomes unequal. 



(3) Examine the demonstration showing that the temperature 

 rises in the middle of a mass of wetted living barley grains and 

 not in the corresponding mass of dead ones. 



(4) Examine the demonstration showing the rise of tempera- 



