LESSONS IN BOTANY. 249 



forest trees. Sometimes lichens or algae are the pioneers in 

 such invasions, which are often very rapid in tropical regions. 

 It is said that an island of lava, from the eruption of Kraka- 

 toa was covered from shore-line to summit with an abundant 

 vegetation of ferns and allied plants within six years after the 

 eruption. 



The succession of plants on a tract of land that has been 

 cleared and then allowed to go to waste is interesting. In one 

 case a bit of pine forest had been cleared away and the land 

 abandoned. It was soon covered with weeds and grasses, then 

 quaking aspen and other woody plants began to smother out 

 the herbs, and it seemed as if the aspen was the natural occupant 

 of the soil. After a time, however, little pines began to grow; 

 these grew larger and others started; the aspens began to decay, 

 and in less than thirty years the pines were again in full posses- 

 sion of the ground. 



The illustrations given may serve to suggest a possible 

 explanation of many peculiarities of form and structure, of color, 

 odor and other characteristic features, which exist among plants, 

 and to indicate interesting and profitable lines of study and 

 investigation, which may be pursued in almost any locality. 



The collection and preservation of specimens is an important 

 part of botanical work. A specimen, to be of value, should show 

 roots, stem, leaves, buds, flowers, fruit, all with color and form 

 as perfect as possible. And the label should show the locality 

 and any peculiarity of position or surroundings that might in 

 any way modify the character of the plant, and any peculiarity 

 of the plant that cannot be preserved should be noted. 



Most herbaceous plants may be preserved by drying them un- 

 der pressure. The plant, with its leaves and other parts, should 

 be carefully arranged in a fold of paper, and then subjected to 

 pressure in a discarded book or some kind of a press, which 

 may consist of two boards with a weight of stone. The plants 

 should be aired frequently until they are thoroughly dry. A 

 few trials will enable one to make good specimens of most 

 herbaceous plants. In the case of some succulent plants much 



