y /■.A'///./.s.i//().v J07 



frccjucntl)-, fertilisation results in the suppression 

 cjf certain chambers in the ovar>', and in the 

 consequent failure of the development of the 

 ovules. 



A cross-section of a \'oun_L( oak (j\'ar\' shows a 

 three-chambered structure, each cavity containinj^ 

 two o\ules, so that the ovarj' in this stage contains 

 six o\ules in three chambers. Soon after the 

 act of fertilisation, one of the fertilised ovules takes 

 the lead in growth, starves the other fi\e ovules, 

 and, as it grows, pushes the j)artitions of the other 

 chambers aside, and graduall\- tills ujj the whole 

 interior, converting it into a one-celled structure. 

 This change hajipens also in the birch ; its two- 

 chambered ovar}' becomes one ; and in the lime, 

 though at first it has a many-chambered o\ary, 

 )-et in the ripened fruit there is rarel\- more than 

 one to be found. 



In a few plants, changes of quite an opposite 

 character take place. In the o\ar)' of the datura,' 

 for instance, we find two cells ; after fertilisation, 

 two false or spurious partitions are developed, 

 dividing the original two-celled structure into four 



' Thorn-apple 



