4 ANTONY GEPP AND ETHEL S. GEPP. 



growth has died ofi" above. These laminae are simple, with undulate margins, and in 

 this respect resemble somewhat those of Laminaria saccharina ; but are of course far 

 larger, and arise from a branched stem (figs, la and lb). 



The main stem is attached to the substratum by a dense ramified mass of leathery 

 holdfasts, and is very short (15-22 cm. long), much compressed (5 cm. wide by about 

 1 • 5 cm. thick), in transverse section concavo-convex with rounded margins (fig. 3a, 

 diagrammatic). It is divided above dichofcomously into two branches which are much 

 compressed, two-edged, laxly twisted, simple or 2-3 times dichotomously branched, 

 and much flattened and expanded below each dichotomy. These branches vary in 

 length from 15-105 cm., the younger branches being the longest ; they gradually 

 taper upwards, and before expanding gradually or quickly into the great flat fronds, 

 are reduced to a width of 1 • 5- 2 • 5 cm. when moist, and • 3-0 • 7 cm. when dried. At 

 this thinnest point they tend to decay most readily when being dried. 



The branching of L. grandifolia is dichotomous, and we can find no indication in 

 either the mature or very young specimens that the dichotomies are the result of a 

 splitting of the developed frond such as is characteristic of some of the other species 

 of Lessonia. Further, in some very young plants (fig. 2) of L. grandifolia, which we 

 found growing on Desmarestia harveyana, it is interesting to note that though but 

 1-2 inches long, they are already as much branched as the huge mature plants ; and 

 this shows that the dichotomous branching occurs very early in the life-history of the 

 plant, and is not a feature of subsequent development. 



The structure of the mature lamina, as seen in transverse section (fig. 5a), consists, 

 like that of the stem and branches, of three strata. Externally is a cortex of small 

 brown cells, placed in short vertical rows, and crowded ; beneath it is a subcortical 

 stratum of about 2 rows of rotundate cells twice as large as the cortical cells, and 

 containing a coloured globose mass of contracted protoplasm. This subcortical stratum 

 passes almost at once into the closely packed, short-celled, irregularly flexuose, longi- 

 tudinal hyphse which form the external limit of the medulla and which in transverse 

 section form a band of tissue apparently composed of 8-10 rows of subrotundate cells 

 of varying size ; the interior of the medulla is composed of hyaline hyphse mostly 

 running longitudinally, laxly juxtaposed in the gelatinoid matrix and separated from 

 one another by 1-2 times their diameter. Embedded in this medulla and dotted 

 along an irregular median line, which stretches across the lamina from edge to edge, 

 are a number of trumpet-hyphse, rather resembling those described by Grabendorfer 

 (Bot. Zeit., vol. XLIIL, 1885, p. 645, tab. VI., fig. 11) for L. ovata, but unlike the 

 latter, they are enclosed each in a sheath of very small cells (fig. 5 b). These trumpet- 

 hyphse run in a sinuous course both longitudinally and transversely, and are found 

 even in the youngest plants. They serve, perhaps, as mucilage tubes. When seen in 

 longitudinal section (fig. 7), they exhibit on their walls very fine and faint transverse 

 striations (confer fig. 9). We have failed to find any such trumpet-hyphse at all in 

 any other species of Lessonia (except L. sirmdans; see p. 6), e.g. L. fuscescens, L, 



