CHAPTER XI. 



BOTANY 

 (Continued) 



I. Miscellaneous. II. Correspondence with Fritz Milller. 



III. Miscellaneous. Letter 658 



I. MISCELLANEOUS, 18631866 

 To D. Oliver. 



Down [April, 1863]. 



The following letter illustrates the truth of Sir W. Thiselton-Dyer's 

 remark that Darwin was never "afraid of his facts." 1 The entrance 

 of pollen-tubes into the nucellus by the chalaza, instead of through 

 the micropyle, was first fully demonstrated by Treub in his paper " Sur 

 les Casuarinees et leur place dans le Systeme natural," published in the 

 Ann. Jard. Bot. Buitenzorg, X., 1891. Two years later Miss Benson 

 gave an account of a similar phenomenon in certain Amentiferse 

 (Trans. Linn. Soc., 1888-94, p. 409). This chalazogamic method of 

 fertilisation has since been recognised in other flowering plants, but not, 

 so far as we are aware, in the genus Primula. 



It is a shame to trouble [you], but will you tell me whether 

 the ovule of Primula is " anatropal," nearly as figured by 

 Gray, p. 123, Lessons in Botany, or rather more tending to 

 " amphitropal " ? I never looked at such a point before. Why 

 I am curious to know is because I put pollen into the ovarium 

 of monstrous primroses, and now, after sixteen days, and not 

 before (the length of time agrees with slowness of natural 

 impregnation), I find abundance of pollen-tubes emitted, 

 which cling firmly to the ovules, and, I think I may con- 

 fidently state, penetrate the ovule. But here is an odd 

 thing : they never once enter at (what I suppose to be) the 

 "orifice," but generally at the chalaza .... Do; you 

 know how pollen-tubes go naturally in Primula ? Do they 



1 Charles Darwin (Nature Series), 1882, p. 43. 



333 



