830 POPULAR SCIENCE MONTHLY. 



aid the host-plant in the struggle which it has to sustain, either 

 against rival species or against physical agents. 



The prime origin of the host-organ is really variable, accord- 

 ing to the types considered. Sometimes ants take advantage of 

 cavities wholly or incompletely closed which are a part of the 

 morphological plan of the plant, and the function of which can 

 only be mechanical, such as hollow internodes ; sometimes they 

 convert into ants' nests organs that serve to protect plants against 

 herbivorous animals thorns ; or against physical agencies 

 reservoirs of water. 



In other cases the parasitical origin of the host-organ does not 

 seem doubtful. In some types it may be contrived by the ants in 

 view of their wants perforation of the wall, formation of galler- 

 ies ; in other cases primarily abnormal dispositions determined 

 by the presence of ants in the host-organs seem to become, 

 through heredity and selection, normal organs; ants then find 

 host-organs all ready to receive them, without their having to 

 perform any labors preliminary to putting them to use. Disposi- 

 tions favorable to ants are therefore of multiple origin, varying 

 according to the case. 



The biological relations between plants and ants come thus, 

 by insensible degrees, to affect the complex characteristics of life 

 in common, to reciprocal advantage symbiosis. 



If we examine the phenomena of the world with the eyes of the 

 ancient naturalist we shall not fail to "admire greatly the various 

 means employed by Nature to reach its ends. Regarding the re- 

 lations of ants and plants with reference to the reason for the 

 existence of biological peculiarities, we shall not be able to appre- 

 ciate too much the providence which gives ants access to nour- 

 ishing plants, and furnishes some plants with guests capable of 

 giving them protection in exchange for some small services. 



Does it not seem as if each species was created for the destruc- 

 tion of some other one, and that the life of so many individuals 

 of opposing tendencies should ultimately result in the destruction 

 of all that is living on the surface of the globe ? Yet strangely 

 from the struggle itself is born accord ; the antagonism of beings 

 culminates in symbiosis, instability in equilibrium, death in life. 

 Chaos engenders order. The resultant of these extensive contests, 

 although most usually not appreciable to the eye not forewarned, 

 may be summarized in the word harmony. Perfect accord is 

 established between beings that have nothing in common, pre- 

 cisely in consequence of the diversity of their wants ; for in 

 this accord none of the concordants has an interest in despoiling 

 its associate. 



By this the law of progress is certainly confirmed as to what 

 concerns general life. Aside from the sufferings and the death of 



