562 THE FERTILISATION OF FLOWERS. [PART III. 
colour; the former shows in other respects also remarkable 
approximations to the condition of an entomophilous flower. 
Indeed, if the pollen-grains of Z. /utea, instead of being smooth and 
powdery, became adhesive, the plant might be supposed to have 
attained the rank of an entomophilous species (609, fig. 1). 
Orv. PALM. 
Sabal Adamsoni has a white perianth which contains honey ; 
it is proterogynous and is fertilised by insects (Halictus, Polistes 
gallica). Chamedorea is also entomophilous ; Cocos and Syagrus, 
on the other hand, are anemophilous (177, -p. 61). 
Orv. AROIDEZ. 
397. ARUM MACULATUM, L.—The arrangement of the flowers 
in this species agrees so completely with Delpino’s excellent 
account of Arum italicum (178, 360) that I have little new to add, 
The upper part of the spathe (d,1, Fig. 185) serves as a wide, 
conspicuous entrance, guiding small Diptera (Psychoda) into the 
lower chamber (ce) which forms a temporary prison. The insects 
creep down the dark-red spadix (¢) or sometimes the sides of 
the spathe until they reach the upper part of the chamber (at the 
level of a, b, 1, Fig. 185). At this point several rows of hairs 
(metamorphosed stamens) radiate outwards, pointing slightly down- 
wards, from the spadix, and form ‘a palisade which does not 
prevent the small visitors from creeping down into the chamber 
(c), but afterwards prevents them from escaping when they try 
to fly towards the light. Even when they try to escape by 
crawling up the spadix, the sharp downturned points bar their 
way. 
In the first stage of flowering the stigmas only, which are 
borne by the base of the spadix, are mature; a foul ammoniacal 
smell attracts the Psychodz into the prison, where they cross- 
fertilise the stigmas if they have come from other plants. In the 
second stage the stigmatic papillae wither, and a drop of. honey 
appears in the middle of each stigma, to reward the little visitors 
for their pains. In the third stage the anthers dehisce, and the 
greater part of their pollen falls upon the floor of the chamber; 
the insects dust themselves over and over with it, and finally, 
when the palisade of hairs withers in the fourth period, they pass 
out, and enter another flower in its first stage. 
