494 ANGIOSPERMAE—MONOCOTYLEDONES 



Smooth beetles, not very skilful in flying, would scarcely be capable of transferring 

 the pollen of this apparently adynamandrous plant. The wild plants visited by flies 

 are, according to these investigators, very fertile, while the garden plants or garden 

 escapes visited almost exclusively by carrion-beetles, remain sterile. The presence 

 (smell ?) of carrion-beetles seems to be the reason that flies do not visit such plants. 

 The beetles appear to be attracted more by the imprisoned flies than by the putrid 

 smell, and to have accustomed themselves later to the species because they find booty 

 here. (Cf. Ludwig's abstract in 'Bot. Centralbl.,' Cassel, xlvi, 1891, pp. 38-9.) 



Arcangeli, on the contrary, asserts (Malpighia, Genova, iv, 1890, p. 492) that 

 he has observed several cases of direct pollination by means of beetles. Vinassa 

 (Atti Soc. tosc. sci. nat., Pisa, vii, 1891, p. 317) confirms this. 



The maximum temperature in the spathe is reached about 2.30 p.m., when it is 

 27° C. (as against 24-6° C.) air temperature. 



In a later investigation (Boll. Soc. bot. ital., Firenze, 1897, pp. 293—300) 

 Arcangeli found the maximum temperature between 8-10 a.m., when it was 28° C. in 

 the spathe. A second maximum was observed in the afternoon. The air temperature 

 at these times varied between 20-5° C. and 21-8 C. 



Of these insects imprisoned in the 'bridal chamber' (149, 21, 200) this time 

 only a decreasingly small number were beetles ; most of them were Diptera, par- 

 ticularly the following 3 species — i. Limosina simplicimana Rond.\ 2. Borborus 

 equinus Fall. ; 3. Sphaerocera pusilla Fall., upon which the transfer of pollen 

 devolved, while the presence of some Braconids was of secondary importance. 

 Arcangeli did not observe ripe fruits. 



Visitors. Vide supra. — J. J. Walker (Gibraltar, Ent. Monthly Mag., London, 

 XXV, 1888-9, P- 33) observed carrion-flies (Calliphora vomitoria L., and Scatophaga 

 sp.), and carrion-beetles (Creophilus maxillosus Z., Dermestes vulpinus F., and 3 sp. 

 of Saprinus). 



2917. D. canariensis Kunth. — This species is self-fertile in the Pisa Botanic 

 Garden; Arcangeli, however, says (Nuovo Giorn. bot. ital., Firenze, xv, 1883) that 

 cross-pollination is not excluded. Fruit-devouring insects, probably carpophilous 

 beetles (Cetonia, Oxythyrea, and others), may be considered pollinators, as an odour 

 of pine-apple and melon is perceptible during anthesis. 



942. Arisaema Mart. 



E. Baroni (Nuovo Giorn. bot. ital., Firenze, New Ser., iv, 1897) describes extra- 

 floral nectaries in some species of Aroideae belonging to this genus, which were 

 indigenous to China and cultivated in the Florence Botanic Garden. Nectar- 

 receptacles are here found in the angles of the individual leaf-segments, which are no 

 doubt of importance in cross-pollination. These species possess, particularly at the 

 ends of the leaf-segments, appendages resembling the end of the spathe. The insects 

 creep easily in the direction of the appendage to the nectaries, while others, misled 

 by the similarity of the structure, reach the spadix by creeping over the spathe to 

 that point on its inner surface where it is touched by the former. They creep thence 

 on the spadix into the ' bridal chamber,' where they deposit and collect pollen. 

 {Cf. SoUa's abstract in Bot. Centralbl., Cassel, Beiheft vii, 1897-8, pp. 99-100.) 



