332 THE FERTILISATION OF FLOWERS. [PART I re 
<i] 
re. 
232. CHRYSANTHEMUM PARTHENIUM, Pers :— 
Visitors : Lepidoptera—Sphinges : Sesia tipuliformis, L., s., also Halie u S 
and Foenus (No. 590, III.). - 
233. MATRICARIA CHAMOMILLA, L.—The general structure < s 
the flower agrees with that of C. lewcanthemum, but the receptz 
of the capitalum is always more convex in this plant. d 
As the centripetal development of the florets proceeds, the 
receptacle rises up into a cylinder, rounded off above. Those 
florets which have ceased blooming always occupy the outer he . 
around the cylinder, those that are still in the bud cocupy 
rounded apex, those that are in full bloom occupy the space betwee 
on which insects alight. The result of this peculiarity is that inse 
always come at once to the right spot for obtaining their hooky a 
for fertilising the flowers. 
In regard to conspicuousness, WV. Chamomilla is far inferior to 
C. leucanthemum ; for each capitulum forms a white circle 18 © 
24 mm. in diameter against 40 mm. or more in C. Jeucanthenll 
with a yellow central disk 6 to 8 mm. in diameter against 12 to 15 mm n. 
in the other. Accordingly its insect-visitors are far less numerous 
and less varied. The strong odour which the capitula emit seems 
disagreeable to most bees; only the species of Prosopis, which are 
themselves strong-smelling, are fond of the plant, as they are also 
of Ruta graveolens, etc. The odour seems pleasant, on the o ner 
hand, to flies; they are found abundantly on the capitula, anc 
constitute the chief fertilisers of the plant. 
Visitors: A. Hymenoptera—(a) Apide: (1) Prosopis signata, Py, 39 
ab. ; (2) Sphecodes gibbus, L. 9 ¢; (b) Sphegide : (8) Oxybelus uniglun nis, 
L., ab. B. Diptera—(a) Stratiomyide : (4) Nemotelus pantherinus, L., very 
PM . 8.3 (b) Empide: (5) Empis livida, L., ab., s.; (c) Syrphide: (6) E 
stalis arbustorum, L. ; (7) E. nemorum, L. ; (8) E. sepulcralis, L., ee ay me 
very ab., fp. ; (9) Syritta pipiens, L., very ab., f-p.; (d) Muscide : (10) § 
phaga carnaria, L., ab. ; (11) S. haemarthoo, Mon. ; (12) Pollenia Ves 
F., all three f.p. ; (18) Lucilia cornicina, F. ; (14) Spilogaster nigrita, Fa 
G, Coleoptera—(a) Nitidulide: (15) Meligethes, ab.; (6) Cerambycie 
(16) Leptura livida, L.; (17) Strangalia attenuata, L., both not rare. See 
also No. 590, MII. | + 
234, TANACETUM VULGARE, L.—Several hundred florets are 
united in a flat discoid capitulum, to which radiating margina 
florets would be of no use, since numerous capitula stand clo se 
together almost forming a single surface. The union of capitula 
