LUTHER BURBANK 



only those vegetables of the simplest type which 

 reproduce by splitting themselves in two. In 

 this subkingdom live the death-dealing bacteria, 

 which bring about such human diseases as tuber- 

 culosis and malaria, or such plant diseases as 

 black rot; and the good bacteria, too, which are 

 everywhere, helping us to digest our food, and 

 without whose help the higher subkingdoms of 

 plant life could not exist; and other plants of the 

 same grade. 



The next subkingdom, higher by a step, includes 

 the yeast which we use to raise our bread, or those 

 microscopic vegetables which turn hop juice into 

 beer, apple juice into cider and rye juice into 

 whisky; and others. Those who prefer to chart 

 seven subkingdoms instead of six, divide this 

 branch into two, making the slime-molds a 

 separate phylum. 



The next subkingdom, ascending the scale, 

 includes, among others, the mosses and liverworts. 



From these it is but a step to the next sub- 

 kingdom, which includes the ferns — the highest 

 type of flowerless plants, and the first, in the 

 ascending scale, to exhibit a complete development 

 of root, stem and leaf. 



The final subkingdom, and the one into which 

 our work principally takes us, embraces those 

 plants which produce seeds. 



[218] 



