216 



The Irish Naturalist. 



December. 



dead specimens of the dipterous insect, Psychoda phalae- 

 noidcs, were found, the numbers ranging from 3 to 30 per 

 spathe. According to Kirchner {he. cit.) this is the only 

 insect proved to effect pollination of the Arum, and as 

 many as 4,000 individuals have been found in a single 

 spathe. 



Numerical variation in Arum maculniuiu is by no means 

 confined to the ovules and seeds. It extends to the whole 

 inflorescence, which, as is well known, is made up of four 

 distinct members or divisions, the female flowers or })istils, 

 the pistillodes, the male flowers or anthers, and the stami- 

 nodes, taking tliem in order from below upwards. The range 

 of variation and the average for each of these divisions of 

 the inflorescence is set out in the following table founded 

 as regards the pistils on an examination of 204, and as 

 regards the other members of 123 spadices. 



Numerical variations in the inflorescence of Arum 



maculatum. 



The most remarkable colour-\ariation observed was a 

 species of albinism in which the club-shaped extremity of 

 the spadix, usually a deep crimson-purple, was cream- 

 yellow or yeUow blotched with green. Out of 204 flowering 

 spathes examined, 20 showed the latter variation, the colour 

 of the club suggesting mouldy Stilton cheese ; only 5 showed 

 the cream-yellow variation. As a rule the pale-clubbed 

 si)adices bore pale yellow anthers and staminodes, though 

 in some cases the colour was pale pink, whereas in the 

 ordinary purple -clubbed spadices these members were red 

 or purplish. 



