CHAPTER XI. 



BOTANY 



(Continued) 



I. Miscellaneous. — II. Correspondence with Frits Miillcr. — 



III. Miscellaneous. letter 6 S 8 



I. Miscellaneous, 1863— 1866 



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 naturel," published in the 

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

 gave an account of a similar phenomenon in certain Amentiferae 

 {Trans. Linn. Sac., 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 locked 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. Hut 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 Dan Nature Series 1, 18S2, p. 43. 



