1843-1862] IN 1. I FERTILISATION 



interested by the abstract (too brief) ol your 1 cture at the Letter 589 

 Royal Institution. Many of the: luded to are full of in- 



terest for me. But on cue point 1 should be infinitely obli 

 if you could procure mean) information: namely, with r 

 to sweet-peas. 1 am a greal bi liever in the natural cr 

 of individuals of the same species. Hut I have been a ui 

 by Mr. Cattell, 1 of Westerham, that the several varieties -l 

 sweet-pea can be raised close together for a number of y< 

 without int< rerossing. But on the other hand he stated that 

 they go over the beds, and pull up an) - false plant, which 

 they very naturally attribute to wrong seeds getl mixed 

 in the lot. After many failures, I succeeded in artificially 

 crossing two varieties, and the offspring out of the same 

 pod, instead of being intermediate, was very nearly like the 

 two pure parents ; yet in one, there was a trace of the cross, 

 and these crossed peas in the next generation showed still 

 more plainly their mongrel origin. Now, what I want to 

 know is, whether there is much variation in sweet-peas which 

 might be owing to natural crosses. What I should expect 

 would be that they would keep true for many years, but that 

 occasionally, perhaps at long intervals, there would be a 

 considerable amount of crossing of the varieties grown cl 

 together. Can you give, or obtain from your father, an)' 

 information on this head, and allow me to quote your 

 authority? It would really be a very great favour and 

 kindness. 



To J. U. Hooker. 



■* !.• iter 590 



The genera Sccevola and Leschenaultia, to which the following letter 

 refers, belong to the Goodeniac :eae <(>oodenovie;r. Bentham & Hool 

 an order allied to the Lobeliaceoj, although the mechanism of fertilisation 

 resembles rather more nearly that of Campanula. The character 

 feature of the flower in this order is the indusium, or, as Deli> .Is 



it, the "collecting cup : ' : this cuplike organ is a development of the 

 style, and serves the same function as the hairs on the style of Campanx 

 namely, that of taking the pollen from the anthers and presenting it to 

 the visiting insect. During this stage the immature stign. the 



bottom of the cup, and though surrounded by pollen is incapable of 

 being pollinated. In most genera of the order the pollen is pushed 

 out of the indusium by the growth of the style or stigma, very much as 



1 The nurseryman he generally dealt with. 



s Delpino's observations on Dichogamy, summarised by Hildebrand 

 in Bot. Zeitung) 1S70, p. 634. 



vol. 11. 1; 



