260 THE JOURNAL OF BOTANY 



secured. In all cases, I gathered one spathe only from each 

 plant. Further, to secure a more reliable result, I abstained 

 usually from gathering more than one spathe from two adjoining 

 groups of plants, whenever it seemed likely that both groups had 

 grown from the seed of one parent plant. In this way I have 

 gathered and counted either spathes or leaves or both from no 

 fewer than 1228 plants — a number large enough, I think, to 

 enable one to arrive at a fairly definite conclusion on the point at 

 issue. The results of my counting are set forth in detail in a 

 tabular statement which follows. 



Before examining those results, however, it is necessary to 

 find terms capable of expressing, definitely and without ambiguity, 

 the two directions in which the spathes and leaves of the Arum 

 are rolled or coiled. For this purpose, I employ the terms 

 " dextral " and " sinistral." These are, I hold (for reasons I hope 

 to set forth elsewhere), the only terms capable of being used in 

 such case without liability to confusion. Let the observer 

 imagine himself to be standing upright, within the spathe (or, 

 better still, within the central stem or axis), facing and looking 

 out of the opening of the spathe. If, in that case, the wing of 

 the spathe, on leaving the central stem or axis as it begins to coil, 

 passes first to the observer's right hand, that spathe is what I 

 call " dextral." If, on the contrary, it passes first to the observer's 

 left hand, the spathe is what I call "sinistral." (It should be 

 remembered that, if the observer imagines himself to be outside 

 the spathe and facing its opening, the conditions are exactly 

 reversed.) The annexed illustration shows a dextral and a sinis- 

 tral spathe of A. viaculatum, as well as a transverse section 

 through the " bulb " of each, the sections being viewed, of course, 

 from above. In each case A represents the central stem or axis 

 (within which the observer is supposed to be), and B the point 

 he is supposed to face as he looks out of the opening of the 

 spathe. 



Turning now to the results of my counting, as shown in the 

 tabular statement annexed, it will be seen that, of 1228 Arum 

 spathes, gathered at random, on thirty-two different occasions 

 between 25th April, 1909 and 10th May, 1914, from hedgebanks, 

 roadsides, ditches, and woods, at various places, chiefly in Essex 

 and Gloucestershire, 645 proved to be sinistral and 583 to be 

 dextral — a majority of 62 for the sinistral spatlies. It is clear, 

 therefore, that, among the 1228 spathes examined, the sinistral 

 spathes stood to the dextral spathes in the same relation that 

 100 stands to 90. In other words, the sinistral spathes out- 

 numbered the dextral spathes by about 10 per cent. 



It is worth noting that we get much the same result if we 

 take the results of the thirty-two observations separately. Thus, 

 no fewer than nineteen (or about 60 per cent.) of these obser- 

 vations yielded a majority of sinistral spathes ; only eleven (or 

 about 34 per cent.) yielded a majority of dextral spathes ; while 

 in two the numbers of each kind of spathe were equal. 



The numbers of observations made and of spathes counted are, 



