522 THE POPULAR SCIENCE MONTHLY. 



THE DEFENSIVE ARMOR OF PLANTS. 



By M. HENRY DE VARIGNY. 



WHILE, as Darwin and his successors have established, plants 

 are dependent to a considerable extent npon insects for the 

 means of securing the fertilization of their seed, they are also 

 liable to be eaten by them, and are in great danger from the vora- 

 cious appetites of other animals. They are not, however, wholly 

 without defense against these attacks, but are provided with 

 armors of various kinds, by the aid of which they offer a more 

 or less effective resistance to them. These methods of defense 

 have been the subject of special investigation by Prof. E. Stahl,* 

 of the University of Jena, whose work, "PfLanzen und Schnecken" 

 (June, 1888), presents a most interesting chapter in the history of 

 the vegetable struggle for existence. 



While every plant has its enemies more or less numerous and 

 dangerous, the number as a whole is not generally considerable. 

 Some attack the young plant, others the adult ; some one part of 

 it, some another. They would, perhaps, be more numerous were 

 it not for the effectiveness of the means of defense that the plant 

 can present against them. These means are various, but without 

 them vegetable species would disappear very quickly. The pro- 

 tection conferred by them is evident, but an enemy more or less is 

 much for a plant. It is sometimes a question of life or death. 

 The phylloxera alone has been competent to destroy the vine in 

 France ; and, if ruminants should add their attacks to those of 

 insects against the thyme or euphorbia, those kinds would soon 

 disappear. In some cases, as of thorns or nettles, the armor is 

 easily discovered ; in other cases it is internal, chemical, or toxic. 

 The protection is evident, whatever its nature may be. The ques- 

 tion arises whether it is fortuitous or the result of a selection 

 among plants. We can hardly doubt what the answer should be. 

 Selection has certainly played a considerable part in the matter. 



* Prof. Stahl's study is not the only one that has been made in this line, although it is 

 perhaps the only experimental one. M. L. Err6ra, of Brussels, presented a short memoir 

 to the Royal Botanical Society of Belgium in 1886, in which he pointed out how experi- 

 ments and observations could be carried on in reference to the subject. lie drew up a 

 table in which he classified the means of defense presented by plants as follows -.—Biologi- 

 cal characters : Plants at stations not easily accessible or with organs difficult of access, 

 social plants, vassal plants, bullying plants (simulating dangerous species). Anatomical 

 character's : Hard, cutting, or piercing organs, calcification, silicification, nettle-hairs!, 

 thorns, etc. Chemical characters : Acids, tannins, volatile oils, bitter properties, alka- 

 loids, and glycosoids. M. Errera adds a table of plants known to him which present one 

 or another of the characteristics thus described. But his design was simply to show how 

 great an interest the study might be made to afford. His views are confirmed by Prof. 

 Stahl's researches. 



