292 GLIMPSES INTO PLANT-LIFE 



other, the ovule, is the cell that has to be fertilised. 

 A.fter this there is the subsequent development of 

 the ovule into the seed, and in this seed we may 

 recognise a plant in embryo endowed with powers 

 not possessed by its parent, that enables it to 

 resist extremes of heat and cold which would 

 result in many cases in death to the parent 

 plant. By way of experiment some seeds have 

 been subjected to 40 degrees of cold, and yet 

 have not lost their germinating power, whilst, on 

 the other hand, it is known that seeds of some 

 plants growing in sandy deserts lie baking in the 

 sun for many months in a temperature of over 70 

 degrees, and yet begin to grow as soon as moisture 

 reaches them.^ 



Things to be observed or collected : — Ex- 

 periments to be made in order to sho\\' diffu- 



' From "Nat. Hist, of Plants," p. 554: "It has been proved 

 experimentally that seeds which have heen deprived hy calcium 

 chloride of as much water as possible are not killed even at the 

 boiling point of water." Careful experiment has shown that there 

 are three stages of activity in the life and work of a plant — (i) .V 

 Diiiiiinum or zero, at v\hicli the processes are just jiossible ; (2) a 

 medium stage or optiiiiuin point where the activity is the greatest ; 

 and (3) a inaxi/niiiii stage of heat where growth is arrested. So 

 that we learn that plant-life can suffer from too high a temperature 

 Eis well as that which is too low. 



