526 THE POPULAR SCIENCE MONTHLY. ' 



Among the fruits, the juicy ones are designed to be eaten by ani- 

 mals, which are to serve as the medium for scattering their seeds. It 

 is, therefore, of advantage to the plant to have its fruit valuable to 

 some animal. The fall season affords an excessive abundance of fruits, 

 but the best and most palatable ones are exposed to speedy destruction. 

 It is, therefore, an advantage to animals, especially to birds, and to the 

 plants likewise, if a few fruits have keeping qualities, that is, are able 

 to resist decay, even if it be partly at the expense of their pleasant 

 taste. This is the case, for example, with the berries of juniper, yew, 

 holly, viburnum, and cowberry, whose persistence appears to depend 

 partly on a hard epidermis, partly on chemical qualities ; on an ethereal 

 oil in the juniper-berry, apparently on benzoic acid in the cowberry. 

 Ivy-berries do not ripen till winter. 



Seeds are protected by their hard casings or by chemical substances. 

 The poison contained in seeds may in part answer the purpose of 

 preventing their being consumed by animals ; but many seeds, as for 

 instance the aromatic seeds of the umbelliferaB and other plants, con- 

 tain not poisonous but antiseptic substances. The fatty oil, which is 

 so abundantly present in seeds, is perhaps as valuable as a means 

 of protection as for food. The oil as well as the shell of the seed 

 prevents the entrance of water at low temperatures ; and, unless 

 water is present, the dry seed can not be attacked by the germs of 

 decay. 



If we survey the vegetable products that afford active chemical 

 agents, we shall find that they are predominantly the bark, roots, and 

 seeds. The coloring-matters, the bitter products, the alkaloids, and 

 the poisonous substances are for the most part obtained from these 

 organs. The leaves which afford such powerful matters are generally 

 evergreen. Indeed, there are poisonous plants (among the nightshades, 

 Araceee, and Personates) and certain poisonous bushes (dogbanes and 

 cashews) which are protected by this quality against the teeth of ani- 

 mals. The ethereal oils serve further in many plants, as among the 

 labiates, the rues, the myrtles, and some geraniums, for protection 

 against the heat of the sun, the reduction of temperature produced by 

 the evaporation of the oils compensating in some degree for the insuf- 

 ficiency of the water which the plants are able to draw from the soil. 

 Aside from these particular cases, however, chemically differentiated 

 substances do not occur abundantly in the leaves or the wood of sum- 

 mer-green plants. Yet a protection of the wood against the germs of 

 decay is evidently not at all superfluous. Wounds are often made 

 upon trees by mechanical injuries, dying limbs, etc., from which decay 

 may penetrate to the interior of the tree. Hence, we quite often find 

 the wood rotten in the interior of a living tree. It is, therefore, also 

 an advantage if the wood is defended against the attacks of rot by its 

 finer texture, by gums, or by antiseptic substances like camphor, quas- 

 sine, berberin, or columbin. 



