1903. Pethybridge. — The Leaf-Spots of Arum viaculatum. 147 



plain green " ; from Hereford, " the unspotted form is the more 

 abundant in the proportion of at least five to one " ; from 

 Sussex^ '^almost all here have green leaves, quite 99 per 

 cent. "; from Lincoln, "unspotted plants 250, spotted plants 

 20 " ; and so on. 



The three exceptions all hail from the south of England. 

 Mr. G. C. Walton, F.L-S., of Folkestone, says he thinks the 

 spotted form on the whole is the more abundant. Mr. J. D. 

 Turney gives the same as his opinion, and that of another 

 botanist, for the neighbourhood of Plymouth. And Miss 

 Groom reports for one locality near Hastings, " so far as I 

 have observed, the one with spotted leaves is the most 

 abundant." These exceptions are probably purely local, since 

 from the three counties in which the above towns are situated, 

 other reports stating that the converse is the case have also 

 been received. 



Hence, it may, I think, be safel}^ concluded that in England, 

 as in Ireland, the plant with spotted leaves is much more un- 

 common than the one with plain green leaves. Relatively, 

 the spotted form ma}^ be rarer in Ireland than in England, 

 although I am inclined to think that careful observations may 

 lead to the recording of the spotted form in an increased 

 number of localities in this country. I know of at least three 

 such which have been noted in County Dublin during the 

 past tw^elve months or so, and the attention of field workers 

 might well be directed to this point. 



Passing on to consider the nature and the cause of the spots, 

 considerably more information requires to be accumulated 

 before satisfactory conclusions can be arrived at. Un- 

 doubtedly the immediate cause of the dark purple colour of 

 the spots is the presence of a soluble colouring matter, 

 generally known as anthocyan or er\throphyll, in the cell- 

 sap of certain of the cells of the"^ leaf The same colouring 

 matter, masking the green chlorophyll, also occurs very 

 frequently in various plants ; for instance, to it is due the 

 coloured leaves of our " copper" beeches, hazels, etc. In the 

 cold weeks in spring the young organs of a very large number 

 of our common plants develop this colouring matter, but only 

 to lose it again as the weather becomes warmer and the new 

 organs more sturdy. This transitory colouration has been 



