148 The Irish Nattiralist. juue, 



studied by Pick,^ and by Overton,'' amongst others ; and it 

 would seem from the latter's researches that the colour is a 

 consequence of the increased content of sugar in the leaf at 

 the expense of the starch, induced by the action of low 

 temperature. 



In the case of Arum maculahim further observations are 

 required to settle definitely whether the spots are permanent 

 or transitory, whether a plant which bears spotted leaves one 

 year also appears with spotted leaves the next, and also whether 

 plants grown from the seed of spotted plants produce spotted 

 leaves, or, in other words, whether the spots are hereditary. 



Stahl, in the paper previously quoted,^ points out that a 

 distinction must be made between spotting or variegation in 

 leaves due merely to the action of the immediate environment 

 of the plant, such as shade and moisture, and spotting which is 

 permanent or characteristic of a particular race or variety of 

 the plant. Thus in Ranujiculus Ficaria the leaves with dark 

 splashes and light green patches were developed best on plants 

 in moist and shady places. Such plants, however, when 

 removed to a cold greenhouse came up the following year 

 with only the merest traces of these markings. 



In the case of the spotted Arum, on the other hand, he says 

 we have to do with a race-peculiarit}^ and he adds that in the 

 Botanical Garden in Jena both the pure green and the spotted 

 forms retain their characters from year to year. 



So far as 1 have been able to observe, there is no difference 

 in the habitats of the two forms \ indeed one finds them, as a 

 rule, growing close together in clumps, but I have not found 

 a spotted and an unspotted leaf on one and the same plant ; 

 either all the leaves on one plant are spotted or all plain. The 

 Rev. W. J. Wingate sends me from Bishop Auckland 

 (Durham) a series of leaves illustrating the gradation from 

 leaves plain, through leaves with one spot ; spots few and 

 faint ; spots numerous but small ; spots larger; blotches still 

 larger and more numerous ; and finally splashes very large. 



^ Pick. Ueber die Bedeutung des rothen Farbstoffes, &c. Bot. 

 Centralblatt, 1 883. 



2 Overton. Beobachtungen uud Versuche ueber das Auftreten von 

 rothem Zellsaft bei Pflanzen. Priugsheims /ahrbuecher, 1899 



» Stahl, loc. cit. p. 174. 



