998 SUMMARY OF CURRENT RESEARCHES RELATING TO 



7. General. 



Myrmecophilous Plants.*— M. M. Trcnb adduces fresh evidence in 

 favour of liis theory that the passages iiihahited by ants in the stem of 

 Myrmccod'in iuhcrosa (previously described as M. echinaia) have for tlieir 

 primary function to servo as reservoirs of water to prevent desiccation, 

 and only secondarily become the abode of ants, which may jiossibly then 

 be of some service to the plant ; though he finds tlieni to flourish equally 

 when not visited by ants. The jiassages are developed in the hypocotyl 

 of the seedling at the very earliest period, before it can possibly bo 

 visited by insects. The author adduces a number of examples of a 

 similar protection against desiccation, where there is no question of the 

 water-receptacles being due to the attacks of ants. 



Mjrrmecophilous Plants.f — Prof. F. Delpino continues his observa- 

 tions on thdse plants wliich attract the visits of ants by extra-floral 

 nectaries. In the order Bignoniacere they are especially numerous, 

 amounting to about G6 per cent, of the total number of species in the 

 order. T.iey occur chiefly on tlie u])pcr or under side of the leaf. 



In the Pedaliuese 13 out of 28 si)ecies have extra-floral nectaries. In 

 the Convolvulacea3 a few species only are named. In the Verbenacea? 

 there are all grades, from the entire absence of such organs to their very 

 elaborate development in Clerodendron. In this genus there are 24 

 m\ rmccophilous species ; in Citharoxi/hnn 12. In Scropliularinea), Melam- 

 pynim is a myrmecoi>hiL)ns genus. In Polygonese only very few species 

 are named. In the Euphorbiacea3 there are 56 myrmecophilous species 

 in the Crotoneje, 20 each in the Acalypheae and Hippomanea}, 2 in the 

 Euphorbicfe, none in the remaining tribes. In the Salicincfe and 

 Orchidea) a few species are enumerated. In the Liliaccfe many species 

 of Ltlium have extra-floral nectaries ; in the Smilaceai there are about 

 95 species ; a few in the Dioscoreacea), Ha^modoraccae, and Irideae ; about 

 30 in the Musaceaj, and a few among Palmae. 



Among Filices Pteris oquilina has nectaries at the base of the frond. 

 Among Fungi the honey- secreting spermogonia of the Uredinea? appear 

 to attract flies rather than ants. Ustilagintie also jjrotcct tlie leaves of 

 the host-plant by attracting ants, and thus preventing their being browsed 

 by animals. 



New Myrmecophilous Plants. j — Herr K. Schumann describes in 

 great detail the structure of several hitherto undescribed myrmeco- 

 philous plants, mostly from tropical South America, belonging to the 

 Melastomaccfe. 



Duroia hirsuta (^Amojona liirsuta P. and E.) is a small tree in which 

 the provision for the inhabiting ants is in the form of a chamber in the 

 main stem, contained in a large swelling, of very complicated and 

 perfect structure. Other species described are Cuviera physinodes, 

 belonging to the Rubiaccas, Pleurothyrium macranthiim (Lauraceae), 

 Calophysca fococoidea, Maiaca Guianensis and flcxuosa, and Tococa 

 lancifolia and macrophysca. 



Duroia saccifera, as well as D. hirsuta, possesses also another con- 



• Ann. Jard. Bot. Buitenzorg, vii. (1888) pp. 191-213 (3 pis.). See Bot. 

 Centralbl., xxxv. (1888) p. 295. Cf. this Journal, 1884, p. 81. 



t Mem. K. Accad. Sci. Istit. Bologna, viii. (1888) pp. GOl-50. See Bot. Centralbl., 

 XXXV. (1888) p. 233. Cf. this .Journa!, 1887, p. (520. 



X Priugbheim's Jahrb. f. Wiss. Bot., xix. (1888j pp. 357-421 (2 pis.). 



