100 PROPAGATION OF PLANTS. 



■with abundant moisture, are the requisites for coloring 

 the leaves of plants a deep green, and in Ireland, long 

 known as the " Emerald Isle," they do not have half the 

 sunlight we do, while under the almost cloudless skies 

 on bur Western plains the foliage of plants have a sickly 

 yellowish or grayish green. 



CHAPTER VIII. 

 SEX AND FERTILIZATION. 



At what stage in the evolution of plants differentiation 

 of sex becomes a distinctive characteristic, has not been 

 fully determined. But from what we know of their 

 development, it is quite evident that distinct sexual 

 organs are the result of a progressive movenient from 

 the lower to the higher and more complex organisms. 

 Nothing like sexual organs have been discovered in the 

 simple one-celled plants, or even among those much higher 

 in the scale, like the Mushrooms, Mosses and Lichens, and 

 even in the Ferns and other eryptogamous plants the 

 sexual organs are not clearly defined, although in some 

 they are sufficiently distinct to be utilized in what is 

 called cross-fertilization or hybridizing of species. It is 

 quite probable that in the lower forms of plants the con- 

 jugation of the sexes occurs by a simple coalescence of 

 cells, somewhat as two drops of water brought in contact 

 unite and become one. But as the practical propagator 

 of plants will seldom have occasion to investigate the 

 sexes of the lower orders, they may be passed over here 

 without further attention. 



In a large majority of the plants under cultivation the 

 sexual organs are sufficiently distinct and conspicuous to 

 be readily examined and manipulated, whenever there is 



