1902.] I. H. Burkill — Flower of Ranunculus arvcnsis. 95 



gets better nourished as it progresses from, the formation of sterile 

 protective or showy organs, through male organs to female organs, or 

 that the female organs appropriate two shares of nutriment because there 

 is by them that which might belong to an elongating axis ? 



Regarding the third kind of question, let it be remarked that 

 intermediate organs are apt to be useless organs and that therefore we 

 see one reason for the distinctness of the moods ; secondly, it is 

 to be stated that if we let ourselves believe that sepals, petals, 

 stamens and carpels are formed under conditions of nutrition which 

 change as the axis gives rise to them, we still cannot easily assume 

 that the conditions of nourishment change as abruptly as do the 

 moods. 



Lastly, with regard to the fourth kind of question we are bound to 

 suppose that a certain relationship between the number of the stamens 

 and carpels exists which is at least not prejudicial to the maintenance 

 of the race ; i.e., that enough stamens must be produced to enable a 

 sufficiency of seed to be set by the carpels ; and it is reasonable to 

 believe that the petals and the sepals are required by their biological 

 functions to bear a more or less definite proportion to the organs they 

 protect or make conspicuous : but it will be acknowledged that this 

 supposition implies a force too loose in its action to produce isomerism 

 as we see it, too loose to regulate the not uncommon orderly chauge of 

 a normally tetramerous flower to pentamerism, or of a normally penta- 

 merous flower to hexamerism, and impossible to accept as the sole 

 factor when we glance at the general absence of intermediate conditions 

 between isostemony and diplostemony. The view to which Schwendener's 

 and Karl Schumann's work leads, can carry us a step beyond this 

 supposition ; for, as they have shown, we have strong reasons for 

 believing that the symmetry of a flower is largely influenced by the 

 mutual pressure in the bud of part on part, and that this pressure to 

 a considerable degree compels new organs to appear in the niches 

 between those recently formed. Thus do the sepals — the outermost 

 members of the flower — as it were set the step and, e.g., if they are in 

 rings of five (I use the word ring because I require a term less definite 

 than whorl ) the petals and stamens frequently follow in fives. 



The carpels too may follow the step, but their position is unique 

 in that the axis is no longer growing forward when they form and new 

 conditions of pressure, as perhaps of nutrition, are possibly existing. 



The individual and the race are always in slight antagonism : the 



race asks for reproduction, and some writers such as Axell have 



thought that they could see in the flower the most perfect adaptation 



or subservience to reproduction, But our flower, above conceived, 



J, n. 13 



