246 PLANT LIFE 



wheat) with " albumen " or endosperm. It 

 is a very remarkable fact, this second fusion. 

 The sperm nucleus which takes part in it is 

 the sister nucleus of that sperm which fuses 

 with the egg. Hence it might be expected 

 that it would carry paternal characters, and 

 that these might make themselves felt in 

 the nature of the endosperm to which the 

 triplicate nucleus gives rise. It turns out 

 that the expectation is realised, and where 

 the endosperms of the pollen parent and the 

 seed parent differ in a well-defined character, 

 e. g. in colour or sugar contents, the char- 

 acter imported by the sperm from the pollen 

 may dominate the whole endosperm. Thus, 

 when pollen grains of different varieties of 

 Indian Corn are blown on to a female ear, 

 the endosperm of some of the grains will be 

 found to be affected by the characters borne 

 by the strange pollen. And it is just these 

 identical grains that will betray evidence of 

 hybrid characters in the embryo which each 

 of them contains. For the same pollen grain 

 provided both the sperm for fertilising the 

 egg, and also the second sperm which formed 

 part of the triplicate combination from which 

 the endosperm originates. 



When fertilisation has been accomplished, 

 remarkable changes are produced, not only 

 within the ovule, but outside it as well. 

 Within, the endosperm arises, by the re- 

 peated division of the triplicate nucleus as 

 already explained, while at the upper end 



