114 THE AMERICAN BOTANIST. 



largest is the Carpomyceteae of fungi with 145. Each family, 

 order, sub-class, class and phylum are briefly described and 

 show more clearly than usual the relationship of the plant 

 world. 



Vitality of Plants — The vitality of many plants seems 

 largely a matter of moisture. A plant that cannot endure 

 frost, and which, of course, would be killed by a heat many 

 degrees below the boiling point of water, can cut off its seeds, 

 each of which contains a plant like its parent, and after these 

 are thoroughly dried, they may be subjected to heat above the 

 boiling point or exposed to the greatest degree of cold that can 

 be produced and escape unharmed. Give these seeds water, 

 however, and they act exactly like the parent plant in their 

 relations to heat and cold. The change in the seed, which 

 enables it to endure extremes of heat and cold, while due 

 largely to lack of water, is also due to other causes, for the 

 protoplasm becomes harder, more granulose and denser, and 

 changes somewhat in chemical composition. 



The Flowers of the Hop. — The hop {Humulus lupu- 

 lus) is one of the plants known as dioecious, that is it produces 

 pistillate (female) flowers on one plant, and staminate (male) 

 flowers on another. Some recent observations by W. W. 

 Stockberger have shown that the power to produce stamens 

 is latent in the case of the female plant and flowers containing 

 both pistils and stamens have been seen. A second observa- 

 tion bearing on the same phenomenon is that the underground 

 runners which produce new plants may give rise to plants that 

 are of the opposite sex from the plants which produce the 

 runners. The question of the origin of dioecious flowers has 

 yet much of mysteiy about it. In all probability the flowers of 

 different sexes have been formed by the dropping out of one 

 set of essential organs in each, but how this has been of ad- 



