THE INDIFFERENT COILING OF ARUM SPATHES 259 



first appear above ground (which is often as early as January or 

 February), the spathe is ah'eacly fully formed, though, of course, 

 very small and still entirely below ground. By pulling up the 

 plant and splitting it open, one can easily ascertain, even at this 

 early stage, which way its spathe is rolled. 



The facts noted in connection with the aestivation of the leaves 

 and spathes of the Arum have long seemed to me curious and 

 anomalous ; for Nature does not, as a rule, leave matters of this 

 kind to chance (so to speak). In most similar cases, she follows 

 some definite rule for each species or each genus, as the case may be. 

 Thus, among climbing plants, a majority (as the Wliite Convolvulus 

 and the Scarlet Eunner) revolve their shoots and tendrils in one 

 definite direction, while others (as the Hop and Honeysuckle) 

 revolve in the opposite direction.* Darwin observes f that, in 

 almost all climbing plants, members of the same genus revolve 

 their shoots and tendrils in the same direction. The same is true, 

 I believe, of the aestivation of the flowers and leaves of all plants 

 having flowers or leaves which are coiled or rolled in their earlier 

 stages — that is to say, in each species or genus, the flowers or 

 leaves are regularly coiled or rolled either one way or the other : 

 not either way indifl^erently. Again, among mollusca having 

 helically- or spirally-coiled shells, a large majority of species coil 

 in one definite direction, though some species coil in the opposite 

 direction. In most species of mollusca, however, one meets 

 occasionally with abnormal individuals coiled in that direction 

 which is opposite to the direction normal in the species — a 

 peculiarity which is much commoner, for some unexplained 

 reason, in some species and in some localities than in others. | 

 The case of the spathes of A. maculatum is, however, totally 

 different from any of the foregoing cases ; for, as stated already, 

 the spathes of this species are coiled or rolled either way in- 

 differently. Similar cases are, I believe, rare in Nature. 



In view of these facts, it occurred to me, several years ago, 

 that it might be worth while to undertake investigations with a 

 view to ascertaining whether plants of the Arum, having leaves 

 and spathes coiled either in one direction or the other, occur in 

 Nature in about equal numbers ; or whether plants having their 

 leaves and spathes coiled in one direction or the other are in a 

 majority. 



Accordingly, I began a series of investigations, which I con- 

 tinued at intervals for five years. During country walks or in 

 odd moments wherever I happened to be (often in shrubberies 

 attached to my own garden), I gathered spathes of the Arum, 

 afterwards counting and recording the number of each kind I had 



* See Darwin, Climbing Plants, 2nd ed., pp. 23-35 (1875), and Dr. B. 

 Daydon Jackson, Glossary of Botanic Terms, 2nd ed., p. 3G7 (1905). The 

 majority revolve in tlie direction which Darwin calls (oj). cit., p. 33) "against 

 the sun." 



t Darwin, oj). cit., pp. 33-34. 



I See J. W. Taylor, Monograpli of Land and Freslncater Mollusca of British 

 Isles, i., pp. 23-2-1, 108-109 (1900). 



u 2 



