STIGMARIA FICOIDES. 



PI. II, fig. 4, represents a fine specimen in Professor Green's collection at the 

 Leeds College of Science. 1 This specimen measures 50 inches from a to & and 36 

 from c to d. Though marked as usual by longitudinal cracks and corrugations, its 

 surface is smooth contrasted with that of Fig. 3. The lines of demarcation between 

 the four roots are not exactly crucial, as is also the case in Plate II, fig. 6. The 

 growth of two, a and b, has probably been a little in advance of that of the 

 other two, which seem to have been pushed asunder by the former. Another 

 striking feature in this specimen is the length attained by each of the four roots, 

 especially by a, without dichotomising. This variability in the conditions of these 

 roots in different individuals was probably dependent on local states of the soil 

 into which the roots had to penetrate. An instructive illustration of this proba- 

 bility is afforded by Mr. Binney in his description of the Duckinfield specimen, 

 now in the Owens College Museum ; one of the primary roots, 3 feet and 1 inch 

 in circumference, extended horizontally for sixteen inches, when it divided into two 

 secondary branches ; each of these again divided into two others, one of which ran 

 horizontally to a distance of fifteen feet from the central stem, without any further 

 subdivision. These four ultimate branches alone exhibited the rootlet-scars 

 characteristic of Stigmaria. On the other hand, the St. Helen's tree presented a 

 very different appearance. Its primary roots penetrated the fireclay at angles, 

 varying from 50° to 60°, before assuming the horizontal direction. In the former 

 case the roots encountered a stiff clay, which they did not penetrate freely ; those 

 of the latter example had eight feet of silty clay beneath them, into which they 

 plunged more easily. 



Plate III, figs. 5 and 6, represent an instructive specimen sent to me by Mr. 

 Geddes, the Librarian of the Blackburn Free Library. Being the base of a much 

 younger tree than any hitherto described, it illustrates one or two points of 

 interest not seen in any other example that I am acquainted with. The entire sur- 

 face of the specimen being covered with the characteristic rootlet-scars, it is obvious 

 that it consists wholly of four coalesced roots, no portion of the true aerial stem 

 remaining in connection with it. It further demonstrates that the absence of all 

 traces of the rootlet-scars from most of the large specimens is due, as I have already 

 suggested, to superficial decortication and not to their previous non-existence. A 

 comparison of the general outline of Fig. 5 with that of Fig. 1 suggests, as already 

 remarked, that the latter example also represents roots only. The maximum height 

 of Fig. 5 above the table, when standing upon its four rootlets, is only 6 inches ; the 

 diameter of its upper extremity, a, is about 6 inches. From c to d it measures 10 

 inches. The mean diameter of the broken end of the root d is slightly more than 2^ 

 inches, the corresponding part of c being 2\ inches. The diameter of the root d 



1 This figure is lithographed from a drawing made for me by Miss Beatrice Boyle, of Leeds, who 

 promises to become a valuable auxiliary to scientific investigators who are not themselves artists. 



