THE DEVELOPMENT OF THE FLORAL WHORLS. 195 



of flowers possessing a corolla is Calyx, Pistil, Stamens, 

 Corolla. As examples, I find tlie following illustrate this 

 condition : Ranunculus scelerafus, Cardamine Jiirsuta, Cerastiuin 

 glomeratwm, Arenaria trinerva, Sagina procuinhens, Spergu- 

 laria marina, Polycarpon tetrapJiyllum, TrifoUum minus, 

 Epilobium mojitanum, Gaura parvijiora, etc. This appears to 

 be the most general condition for very small and incon- 

 spicuous flowers which are regularly self-fertilised. The 

 interpretation is the exact converse of the order of develop. 

 ment first described ; namely, of the whoi-ls of conspicuous 

 flowers. All the above are inconspicuous, many being rarely 

 if ever visited by insects ; and as the corolla is minute, no 

 nourishment is required for the j^etals, the stamens are often 

 reduced in number and the quantity of pollen diminished. 

 The pistil at once proceeds to grow, and the result is, if not 

 homogany, protogyny. 



It must be now borne in mind that the above differences 

 in the order of growth and development must not be regarded 

 as at all absolute or invariable, but only general rules as to 

 what takes place ; for the rates of growth of the respective 

 whorls may vary in the same species according to external 

 circumstances ; so that a plant may be protandrous at one 

 time or place, homogamous or even protogynous elsewhere 

 or in another season, as the case may be. Indeed, Miiller 

 frequently calls attention to this fact, to which I shall have 

 occasion to return. 



Emergence and Development of the Ovules. — If the 

 ovules be tolerably numerous, the order in which they appear 

 is not constant. It may be either from above downwards or 

 from below upwards on the placenta. Thus, as Payer has 

 shown by his drawings, in Viola, Reseda, Cistus, Tetrapoma, 

 Fmnaria, Linum, Buta, Melianthus, Staphylea, Spircea, and 

 Opuntia the order is basifugal, or from below upwards. On 



