THE FRUIT AND SEED-DISPERSAL 



i -> " 



grain taken from an ancient Egyptian sarcophagus and sown by horticul- 

 turists has ever been known to germinate : nor is there any trustworthy 

 evidence up to the present date. The condition of grains known to have 

 been taken from mummies is as though they were charred, and the germ 

 perished. On the other hand, seeds of Nelumbium from Sir Hans Sloane's 

 collection were germinated by Robert Brown after being dry for at least 

 1 20 years. 



Low temperature arrests physiological activity : but Brown and Escombe 

 showed that the vitality of seeds is not destroyed by exposure even to extremes 

 of cold. They submitted seeds of twelve plants of different affinities to a 

 temperature varying from 183 to 193 degrees below zero centigrade, for over 

 100 hours. As a result their powers of germination showed no appreciable 

 difference and they produced healthy plants. 



Cycle of Life. 



The germination of the seed, and the re-establishment of the 

 sporophyte as its result, completes the normal cycle of life of the 

 Flowering Plant. The leading incidents of that cycle may be repre- 

 sented by a diagram, which will serve later as a means of ready 



VeCPsop', 



Sporophyte, 

 (Diploid) 



Microspore. Mecaspore. 



CoNTOrrsOr 



Embryo -Sac 



(Haploid) 



CONTENTS Of 



Pollen-grain -tube 



Fig. 257. 



comparison with types of vegetation lower in the scale (Fig. 257). It 

 will be found in them all that the leading events succeed one another in 

 a sequence that is uniform, however different the details may appear. 

 Two critical points in the cycle are marked by the fact that the 

 individual life is there presented in each case by a single cell. They 

 are the Spore and the Zygote : the former follows on reduction, and 



