64 THE PLANT WOELD. 



tions any more securely or certainly than the humhlc annuals 

 that have attained hy certain habits all the advantages that their 

 more conspicuous neighbors have gained by costly strnctural 

 adaptations. Itather it would seem that the winter annual 

 might 1)0 compared to the light armed soldier who wins the 

 day with only a fraction of the real danger which one with a 

 ponderous coat of mail and long exposure experiences. Certain 

 it is that onr winter annuals are a highly successful species. 



Disconi'nntous Yaridiion. (tiul llic Evohdwn of Seeds. The 

 first part of the opening address of Professor ¥. W. Oliver, 

 before the Botany section of the British Association, at the 

 York meeting, 1906, is entitled, "The Seed, a Cliapter in 

 Evolutiou." The recogniition of the sti-uctnral identity of the 

 dilferent parts of the seed and flower is one of the most difficult 

 problems of plant morpliology. .Vftcr giving a detailed dis- 

 cussion of the seed strnctnre in the Pferidos-pcniis, (Jiinino- 

 spcrms and the Angiosprrms. Professor Oliver em]>hasizes the 

 fact that "In olancino- liack at \ho oarlv seed structures, one 

 is struck with the complexity of their organization as compared 

 with the relative simplicity of modern seeds. "' '" ■" This re- 

 duction in complexity may be accounted for on two grounds. 

 In the first place, fertilization by motile sperms has been replaced 

 by fertilization hy pollen-tubes. Instead of sperms being dis- 

 charged into an internal water chamber upon which the arche- 

 gonia abutted, tlie male cells are carried through soft tissues 

 to the egg in a jdastic tube. * " '" lust at what stage the 

 improvisation of the pollen chamber gave place to the newer 

 method we have no knowledge." 



"The other cause that must have played a ])roniinent part 

 in the simplification of the seed was the association with it 

 of other structures which relieved it of a part of the original 

 load of duties that fell to its lot." The best example of this 

 is the Angiosperm ovary, l>ut "The steps 1)V which this came 

 about remaiu hidden, and anv discussion of the matter is of 



