no 



I. H. Burkill — Flower of Ranunculus arvensis. [No. 2. 



Mathematical expression of the curves in formulae seems to be by 

 no means impossible al though they are complicated. 



There is no fiat which says " this will be a flower of Ranunculus 

 arvensis, the organs may vary in number a little from the ideal." But 

 the fiat says " this will be a flower and must run throughout all its 

 moods. So long as all are present let them jostle for their compliment." 

 So they jostle and the older win as far as they may by being already 

 established at the time when the younger begin to compete; the sepals 

 take what they want only being forbidden from getting the whole five 

 when that would leave too little for the other moods ; and the petals 

 following claim their portion in the same way but a little less strongly. 

 There is left a residue for the stamens and carpels, and the larger 

 it is, the more organs do the moods of both sets, but especially the 

 stamens, obtain. 



Nutrition. — If seeding be prevented, Ranunculus arvensis dies 

 flowering in utter depletion. Therefore I could get from this little 

 proletarian flowers formed under the best conditions and under the 

 worst possible conditions of nutrition, and so seek the effect of star- 

 vation on the moods spoken of. My earlier paper (Journ. Linn. Soc, 

 Botany, Vol. XXXI, p. 235) contained a note on this plant to show that 

 in it, as in several other plants, the first formed flowers are richest in 

 stamens and carpels ; I can now give fuller statistics, and shall show 

 distinctly that the flower is pauperised with the ageing of the plant. I 

 have divided the flowering period of the plants grown in 1895 into 

 three periods and of those grown in 1898 into four periods. The de- 

 crease with age in the number of parts in the flower is shown by the 

 following averages : — 



Table XVIL — Kew, Old. Average number of organs in flowers at 

 different periods. 



Sepals 

 Petals 

 Stamens 

 Carpels 



Period 1. 

 6th July to 

 17th July. 



4-99 



4-95 



11-58 



6-78 



Period 2. 



18th July to 



29th July. 



4-98 

 4-85 

 7-81 

 5-97 



Period 3. 

 30th July to 

 10th August. 



4-99 

 4-66 

 6-17 



5-28 



Period 4. 



11th August 



to 23rd 



August. 



4-89 

 3-95 

 4-93 

 415 



