A CHAT ABOUT THE COROLLA. 223 



of the seed. We may cite, as an example, a Brazilian species 

 of Urticaceae, which Saint-Hilaire named the Elasticaria. The 

 fleshy and cylindrical parts of the calyx are curved inwards, 

 and thus defend, as one might do with one's bended fingers, 

 the young fruit until it is completely developed ; as soon as 

 the fruit is ripe, they spring up erect, and launch it to a 

 distance. 



The Corolla. If from the circumference we proceed to the 

 centre of the flower, the calyx being the first, the corolla will 

 be its second envelope. 



If, on the contrary, we proceed from the centre to the cir- 

 cumference, the corolla will form the fourth whorl ; the pistil 

 (consisting of stigmata, stylus, and ovary) being the first; 

 the nectariferous disc (often wanting) the second; and the 

 stamens the third whorl. Remarkable for its varied tints, 

 the corolla, to indifferent or ignorant eyes, seems the entire 

 flower. 



A black or blackish colour is exceedingly rare. Out of 300 

 vegetable species which compose the flora of Central Europe, 

 there are not six with blackish or even grayish flowers. No 

 hypothesis has yet been put forward to explain this mark- 

 worthy rarity. 



Species with a yellow corolla are the most numerous, form- 

 ing more than a sixth of the European flora : then come, in 

 their order of frequency, species with green, white, red, and 

 blue flowers ; the white increasing in number as we approach 

 the Pole. 



