486 THE UNIVERSE. 



Other plants display a still more remarkable pheno- 

 menon, for in them the same flower changes its colour at 

 different hours of the day. This happens with the Hibiscus 

 m.utabilis, the corollas of which are white in the morning, 

 become rose-coloured toAvards the middle of the day, and 

 in the evening take on a beautiful red tint. 



The successive change in the tints of the corolla is easily 

 conceived ; it may depend on vital action or on chemical 

 reactions effected by time; but what is much more difficult 

 to explain is, that flowers having displayed a certain cate- 

 gory of changes during the day, go through the same 

 round of variation the day following. This is observed in 

 the variously coloured corn-flag {Gladiolus versicolor, 

 Linn.), the corolla of which, brown in the morning, becomes 

 blue in the evening, and on the day following takes on 

 again exactly the same succession of tints as it showed the 

 day before.^ 



What a variety of perfumes the flower possesses ! And 

 yet notwithstanding their thousand and one shades of dif- 

 ference, those Avhose sense of smell is sharpened by prac- 

 tice can distinguish that of each species. 



It is even stated in some works that a young American, 

 who had become absolutely blind, botanized, guided by 

 the smell only, in the midst of prairies enamelled with 

 luxuriant vegetation, and never committed any mistake in 

 his gleanings. 



The odours which exhale from plants are almost always 

 delightful; it is only rarely that they are repulsive. 



1 It is now, too, a wen-established fact that in many plants certain members 

 occasionally change their colours for a season or two. The number of such 

 varieties is greater than was supposed ; thus, for instance, one contributor alone 

 to t^cience Gossip records white-flowered varieties of four different waj'side plants 

 whicli had come under his own observation in a short time: Geranium robertianum 

 and G. '/nolle, Lamiumjna-jnireian,dL'DdSper(rv,lamarina. — Science Gossip), 16(J5. — Tr. 



