MR. C. DARWIN OK SPECIFIC DIFFERENCES IX PRIMULA. 453 



F. lychnitis and tjiapsus which grew in the same field. All the 

 latter were charged with perfect but immature seeds, whilst the cap- 

 sules of the twenty intermediate plants did not contain one single 

 perfect seed. These plants, consequently, were absolutely barren. 

 Prom this fact, from the one plant which was transplanted into 

 my garden yielding when artificially fertilized with pollen from 

 V. lychnitis and tliapsus some seeds, though extremely ievf in 

 number, from the fact of the two pure species growing in the 

 same field, and from the intermediate character of the sterile 

 plants, there can be no doubt that they are hybrids. Judging 

 from the position in which they were chiefly found, I am inclined 

 to believe they are descended from V, thapsus as the seed-bearer, 

 and V. lychnitis as the pollen-bearer. 



It is known that many species of Verhasciim^ when the stem is 

 jarred or struck by a stick, cast ofi' their flowers *. This is the 

 case witli V, tJiapsus, as I repeatedly observed. The corolla flrst 

 separates from its attachment, and then the sepals spontaneously 

 bend inwards so as to clasp the ovarium ; and by this movement, 

 in the course of two or three minutes, the corolla is pushed off. 

 This does not occur with quite young flowers barely expanded. 

 Verbascum lychnitis and, as I believe, F". phoeniceum do not cast 

 their corollas, however often and severely they may be struck. In 

 this curious property the above-described hybrids take after F] 

 thapsus ; for I observed to my great surprise that when I pulled 

 off the flower-buds surrounding the flowers round which I wished 

 to tie threads as a mark, the slight jar invariably caused the co- 

 rollas to fall off. 



These hybrids are interesting under several points of view. 

 First, from the number found in various parts of the same mo- 

 derate-sized field. That the parent plants should be crossed so 

 frequently is the more surprising, as the species of Verbascum do 

 not secrete nectar; but they are frequented by pollen-gathering 

 bees. Bees, though they devour much pollen, are beneficial to 

 these plants, by crossing distinct individuals of the same species; 

 for I have found on trial that plants raised from crossed seed are 

 more vigorous than those from self- fertilized seed ; on the other 

 hand, as we now see, bees often bastardize and deteriorate the 

 species. Secondly, these hybrids are highly remarkable from dif- 



* This was first obseryed by Correa de Serra. See Sir J. E. Smith's * English 

 Flora,' 1824, vol, i. p. 311. Also ' Life of Sir J, E. Smith,' vol. ii. p. 210. I was 

 guided to these references by the Eev. W. A. Leighton, who observed this same 

 phenomffloon in V, virgatum. 



