A REMARKABLE FORM OF DICRANELLA HETEROMALLA 307 



Great Bedwyn, near Hungerford, Wilts. Subsequently Mr. Hurst 

 traced it for a considerable distance in the immediate neighbour- 

 hood, extending for quite two hundred yards, and forming plenti- 

 ful masses about the roots of trees ; in fact, it seemed as if this 

 abnormal-fruited form was the prevailing one in the locality, the 

 normal form of fruit not being seen. Later on Mr. Hurst traced 

 it for nearly half a mile on Burridge Heath, where it was quite 

 abundant, and where a little of the normal D. heteromalla fruit 

 occurred with it ; subsequently it turned up a mile and a quarter 

 away from its original station, on a bank at Stype Wood; later on 

 at a still greater distance, in Savernake Forest, in two localities, 

 about four miles from the original station. 



The abundance of capsules, the apparently constant absence of 

 D. varia in association, and the great quantity of the male plant 

 of D. heteromalla present, made it pretty clear that the hybrid 

 theory must be abandoned, and some other explanation sought. 

 This was confirmed and indeed demonstrated by some of the later 

 gatherings sent me by Mr. Hurst. For not only did many inter- 

 mediate forms occur between the extreme form as described above 

 and normal heteromalla setae and capsules, but on one or two tufts 

 I found, side by side with the abnormal capsules and on the same 

 stems, setae of last year's fruit exhibiting no difference from 

 ordinary heteromalla ; while later on, tufts gathered in July pre- 

 sented young setae of the present year which were evidently on 

 the road to become the normal, elongate, pale yellow setae charac- 

 teristic of the normal plant."' Clearly therefore the peculiar 

 capsules represent a state or form merely, and that not so much 

 a local as a temporary state, due, one would suppose, to some 

 climatal conditions. What these may have been, however, I 

 cannot suggest. The abnormal capsules appeared to mature 

 principally about the end of May and early part of June. Mid- 

 winter is the usual maturing time for the species, but it varies 

 greatly, and I do not think the simple fact of retardation would 

 itself be sufficient to account for the results. The extremely hot 

 and dry April of this year is perhaps the most marked meteoro- 

 logical feature of the fruiting period of the plants in question ; 

 but it is evident that, for capsules ready for deoperculation in May, 

 the setae must have been fully developed long before the late 

 spring of this year, and as the most, or one of the most, notice- 

 able deviations from the normal is presented by the seta, the 

 cause must be looked for at some far earlier stage. The setae of 

 next year's capsules were showing well above the shoots when 

 gathered in early July this summer, and if the plants were in a 

 similar stage of development last July, the suggestion may 

 be hazarded that the extreme heat and drought of that period of 

 1911 may have been the predisposing cause, followed by an arrest 

 of development which only allowed of maturing late this spring. 



It may be mentioned that in addition to the characters at first 



* Since the above was in type I have received further specimens from Mr. 

 Hurst, gathered on Burridge Heath, in abundant and quite normal fruit of the 

 present year, and still retaining many of the abnormal capsules hero described. 



