74 THE FERTILISATION OF FLOWERS. [PART III. 
Oscinis, and Microphorus, besides small Pteromalide and minute 
Ichneumonide, a small Haltica, some Anthomyie, and a single 
Melanostoma mellina (570, vol. x. p. 129). | 
5. RANUNCULUS AQUATILIS, L.—The yellowish base of each 
petal serves to guide insects towards the honey; on it stands an 
obliquely-placed tubercle, truncate above, and provided with a 
honey-secreting hollow, which plays the parts of gland and 
receptacle for the nectar. . 
The anthers, which are few in number, dehisce one after the 
other when the flower opens, and cover themselves all round with 
pollen; the stigmas become developed at the same time, and often 
come in contact spontaneously with the pollen on the anthers. | 
The flowers are frequented by a large number of insects, 
especially Diptera, which alight sometimes in the middle of the 
flower, sometimes on the edge, and so effect self-fertilisation as well 
as cross-fertilisation. 
A. Diptera—(a) Syrphide: (1) Eristalis tenax, L.; (2) E. arbustorum, 
L.; (3) E. nemorum, L., all three abundant, now sucking, now collecting 
as 
he on pe i i 
pollen, plentifully dusted with pollen on the legs and especially on the soles % 
of the feet; (4) Helophilus floreus, L. ; (5) Chrysogaster viduata, L., also s. 
and f.p.; (b) Muscide: (6) Scatophaga merdaria, F., fp. ; various small 
Muscide, s. and c.p. which escaped me. B. Hymenoptera—Apide : (7) Apis 
mellifica, L. § , ad.,s. and ¢.p. ; (8) Bombus terrestris, L.9,s. C, Coleoptera— 
Chrysomelide : (9) Helodes phellandrii, L., devouring anthers and petals. See 
also No. 590, I., pp. 48, 49. 
When the water is unusually high, the flowers of Ranunculus 
aquatilis remain submerged and do not open, but fertilise 
themselves (17, p. 14, 351, p. 17). eee 
Ranunculus glacialis, L., is slightly proterandrous (Ricca) ; 
R. alpestris, L., is homogamous or slightly proterogynous; 2. par- 
nassifolius, L., and R. pyrenceys, L., var. bupleurifolius, D.C., are 
proterogynous with persistent stigmas. In all these species the 
shape of the nectaries is very variable (609). 
6. RaNnuncuLUS FiLammuLA, L.—The flowers have scarcely 
opened when the outermost anthers dehisce extrorsely, covering 
their sides which are turned towards the petals with pollen, so 
that insects which try to plunder the honey secreted by the little 
scales at the base of the petals must of necessity dust themselves 
with pollen. The stigmas are at this time concealed or almost 
concealed by the inner stamens, and so are ensured against contact 
with insects; they are, moreover, not yet fully developed. The 
