Febriiaiy — March 1SS9.] 



PSrCHE. 



171 



MYRMECOPHILISM. 



BY WILLIAM TRELEASE, ST. LOUIS, MO. 



[Address of the retiring president of the Cambridge Entomological Club, 11 January 1S89.] 



It is customary in some circles for a 

 president's address to consist of a gener- 

 al resum^ in some line of scientific work. 

 I have availed myself of this opportunity 

 to review the more important literature 

 on a branch of biological work which has 

 long possessed an unusual degree of in- 

 terest for me, — namely, the mutual re- 

 lations, amounting in some cases to 

 symbiosis, existing between ants and cer- 

 tain members of the vegetable kingdom. 

 Such a forced review is profitable to 

 the writer, and it may be of interest 

 to the body before which it is read ; 

 but it by no means follows that it has 

 scientific value, for each worker must 

 perforce go back to original soinxes for 

 information needed in his own researches. 

 Qiiite naturally. I have treated the sub- 

 ject from a botanical standpoint, since, 

 with the exception of certain acquired 

 habits, the specializations are chieflv 

 such as fit plants to profit bv the visits 

 of ants to their vegetative or fruitino- 

 organs. 



I. The fl'xctioxs of extra-nuptial 



NECTAR-GLANDS. 



The chief sorts of glands situated on 

 the surface of plants or opening super- 

 ficially, are divided into colleters and 

 nectar-glands, according as the}- secrete 

 resinous, mucilaginous, or gummy sub- 

 stances in the one case, or sugary fluids 

 in the other. The first are apparenth- 



for the most part protective, in that they 

 form a coating over young parts in the 

 bud, which prevents drying or other 

 injur}- ; or they pre\'ent the access of un- 

 bidden guests to the flowers or fruit, or 

 deter vegetable feeders from making an 

 onslaught on the paits which bear them, 

 — in this respect resembling raphides, 

 alkaloids, volatile oils, etc., within the 

 plant.* A few such structures sei-ve for 

 the attachment of fruit or seed to animals 

 for purposes of dissemination, etc. The 

 digestive glands of carnivorous plants 

 may, perhaps, be regarded as derived 

 from some of the numerous tvpes of col- 

 leters, and the foliar nectar-glands of 

 many plants are pretty clearly homolo- 

 gous with the serration- and other col- 

 leters of the same and related species. 

 T}pical colleters are, therefore, chiefly 

 protective, and there is good reason for 

 believing that many of them have been 

 evolved for preventing the access of ants 

 to the flowers of plants, where, almost 

 without exception, the presence of these 

 insects works mischief. 



Nectar-glands, on the other hand, are 

 of indirect use by attracting suitable pol- 



* For a recent discussion of the protection of 

 plants, especially from the attacks of snails, by col- 

 leters and other deterrent structures, see an elaborate 

 paper by Stahl in Jenaische Zeitschrift fiir naturwiss. 

 und medicin, xxii.— reprinted under the title "Pflan- 

 zen und schnecken," Jena, 1888. — Abst. in Bot. 

 centralblatt, 1888, v. 36, p. 164-170. 



