MANUAL OF NATURAL HISTORY. 387 



and are found useful for purposes of study, and ac- 

 cordingly two such have been established, which are 

 determined by the presence or absence of flowers, 

 and of distinct organs of fructification. The first of 

 these, variously named the Flowering, Sexual, or 

 Phanerogamic, is the highest in the scale, and 

 contains all the more important species. As a gene- 

 ral rule, its members attain a much larger size, and 

 are in all respects more fully developed. They pos- 

 sess vascular as well as cellular tissue, or, as these 

 are technically expressed, " parenchyma/" and " an- 

 gienchyma ;" they all have distinct sexual organs, 

 either in the same or in different individuals, that is 

 to say, they are either hermaphrodite or unisexual ; 

 and finally they are propagated by seeds. They 

 compose nearly six-sevenths of the total number of 

 genera and species at present known, the compara- 

 tive proportion being greatest within the tropics, 

 and diminishing towards the poles. 



Flowers have been arranged according to their 

 colour in three series, viz., white, xanthic, and cya- 

 nic, the first including all the pale coloured kinds, 

 the second comprehending the yellows and scarlets, 

 and the third comprising the blue and the pur- 

 ple varieties. The white abound more in northern 

 situations and alpine regions, the xanthic are more 

 common in the tropics, especially during the autumn, 

 while the cyanic flourish in the congenial climates, 

 and under the clear blue skies of warmer parts of 

 temperate latitudes. 



Almost all the vegetable products employed by 



s 2 



