Identity of knagdllis arvensis and cceridea, 537 



they may be truly accounted the most ancient vessels in the 

 world, because their forms, and materials, and equipments, 

 have remained unaltered since the times of the earliest histo- 

 rians. Yours, &c. 



July 31. 1830. John Hogg. 



Art. XI. On the Specific Identity of Knagdllis arvdnsis and 

 cceruka. By the Rev. J. S. Henslow, Professor of Botany in 

 the University of Cambridge. 



Sir, 



Dr. Hooker, in his most excellent British Flora^ still 

 keeps the ^nagallis caerulea distinct from the A, arvensis ; and 

 perhaps the difference pointed out by him in the shape of the 

 petals fully justifies him for so doing in the present uncertain 

 state of our knowledge of the laws which regulate the limit- 

 ation of species, J received last year, from the Reverend E. 

 Wilson, some specimens and seeds of ^nagallis caerulea 

 gathered in Yorkshire. From these seeds I have raised a 

 dozen plants, nine of which have blue flowers, and three have 

 red. Hence it should seem that in future ^nagallis caerulea 

 must be considered as a variety of A, arvensis. I conclude, 

 from the above fact, that whatever may be the cause which 

 disposes the petals of this species to assume a blue colour, 

 this likewise disposes them to become notched or toothed at 

 the margin, as Dr. Hooker has universally observed them to 

 be. Though we cannot say the following law is certain in 

 botany, yet it seems to me very likely to be true, viz. '* That 

 if a change takes place in one of the organs of a plant, a simul- 

 taneous change may be expected in some or all of the other or- 

 gans considered to be modifications of the same organs." For 

 instance, considering the calyx and corolla to be modifications 

 of the leaf, when we see the leaf of the cowslip diiFering from 

 that of the primrose, we need not be surprised to find that 

 the calyx and corolla should differ also, though these plants 

 be not distinct species, as I showed in my communication to 

 the last Number of your Magazine. 



I have met with the light pink variety of A. arvensis at 

 Higham, Kent ; and the gentleman: from whom I received the 

 seeds of the blue variety mentioned in this communication, 

 sent at the same time, and from the same place, some seeds 

 of a white variety, similar to that received by Dr. Hooker 

 from South Wales. From these seeds I have raised seven 



Vol. III. — No. 16. n n 



