1859— 1863] BOTANICAL EXPERIMENTS 221 



to me. But I cannot avoid thinking that there is something Letter 151 

 unknown and deeper in seminal generation. Reflect on the 

 long succession of embryological changes in every animal. 

 Does a bud ever produce cotyledons or embryonic leaves? 

 I have been much interested by your remark on inheritance 

 at corresponding ages ; I hope you will, as you say, continue 

 to attend to this. Is it true that female Primula plants 

 always produce females by parthenogenesis? 1 If you can 

 answer this I should be glad ; it bears on my Primula work. 

 I thought on the subject, but gave up investigating what had 

 been observed, because the female bee by parthenogenesis 

 produces males alone. Your paper has told me much that 

 in my ignorance was quite new to me. Thanks about 

 P. scotica. If any important criticisms are made on the 

 Primula to the Botanical Society, I should be glad to hear 

 them. If you think fit, you may state that I repeated the 

 crossing experiments on P. sinensis and cowslip with the 

 same result this spring as last year — indeed, with rather more 

 marked difference in fertility of the two crosses. In fact, had 

 I then proved the Linuiu case, I would not have wasted time 

 in repetition. I am determined I will at once publish on 

 Linum. . . . 



I was right to be cautious in supposing you in error about 

 Siphocampylus (no flowers were enclosed). I hope that you 

 will make out whether the pistil presents two definite lengths ; 

 I shall be astounded if it does. I do not fully understand 

 your objections to Natural Selection ; if I do, I presume they 

 would apply with full force to, for instance, birds. Reflect 

 on modification of Arab-Turk horse into our English race- 

 horse. I have had the satisfaction to tell my publisher to 

 send my Journal and Origin to your address. I suspect, with 

 your fertile mind, you will find it far better to experiment 

 on your own choice ; but if, on reflection, you would like to 

 try some which interest me, I should be truly delighted, and 

 in this case would write in some detail. If you have the 

 means to repeat Gartner's experiments on variations of 



or the other, it is quite clear that it cannot be an exact diagonal of the 

 two, or it would be of no sex at all ; it cannot be an exact intermediate 

 form between that of each of its parents — it must deviate to one side or 

 the other." 



1 It seems probable that Darwin here means vegetative reproduction. 



