164 CRUGER'S ORGANOGRAPHICAL OBSERVATIONS 



other organs make their appearance, and the latter all show 

 themselves at once, as in the Musaceae. 



The symmetrical arrangement of the parts of a natural object, 

 and of a plant in particular, is so general a law, striking even 

 the uninstructed, that a deviation from it must be considered as 

 a most extraordinary phenomenon. So far as I know, the 

 flower of the Cannaceae is almost the only one that can be re- 

 garded as asymmetrical. A glance at the diagram (PI. V. fig. 5) 

 is sufficient to prove that this flower may be regarded as per- 

 fectly symmetrical, if we assume to exist, in the midst of the two 

 or three flowers which are found together, an axis around which 

 the flowers are arranged in a more or less simple spiral. In this 

 case the anther stands on the side of the hypothetical axis, just 

 as in the Zingiberaceae, and then consequently no distinction 

 can actually exist between these two families. The great irre- 

 gularity which we observe in the full-grown flowers arises sub- 

 sequently through twisting and lateral development. 



Zingiberaceae. Costus spicatus, Sw. While the flower of the 

 Cannaceae is difficult to define at first sight, that of the present 

 beautiful family will be found very easy to understand. Yet 

 after all, as I have endeavoured to show above, it is only the 

 inflorescence which causes these difficulties. Among the proofs 

 of this is the circumstance that the same difficulties occur in 

 the Zingiberaceae, if the inflorescence is not properly inter- 

 preted ; only the matter is simpler here from the flowers being 

 regular. 



A glance at the diagram of Costus (PI. V. fig. 6) will give an 

 idea of the mode of arrangement of this flower and its rela- 

 tion to the axis and bract. Here the labellum is assumed to be 

 a simple element, but in many Zingiberaceae, as is well known, 

 two little leaflets occur at its sides, which are more or less con- 

 nected with it. The labellum of this species is three-lobed at 

 the apex with very inconsiderable indentations ; there is an addi- 

 tional smaller lobe at each side. The leaves of the species of 

 Costus are, as is well known, arranged in very distinct spirals, 

 and there also exists a twisting of the axis. The spiral of the 

 leaves is much contracted in the spike ; behind each bract stands 

 a solitary flower with a small lateral involucral bract (deck-blatt), 

 which stands in front of the flower in the direction of the prin- 



