Laing. — On Lessonia variegata. 309 



speaking of L. nigresccns, in which, no doubt, is partly in- 

 chided L. variegata. However, such a series of rings can only 

 with difficulty be made out in our New Zealand specimens. 

 On a stem of one of these being cut across there is to be seen — 

 (1) The thin brown epidermal and cortical layer ; (2) a lighter 

 tissue (almost white in spent specimens), which constitutes 

 the great bulk of the stem ; (3) a darker tissue, oval in trans- 

 verse section, and scarcely to be distinguished by the naked 

 eye from (4), a linear more or less central layer, containing 

 brown colouring -matter. It is in No. 2, particularly in 

 •dried specimens, that faint concentric rings are to be seen ; 

 but I have not been able by microscopical examination to 

 ascertain that they are rings of growth, as Hooker thought 

 they were, or even to differentiate them at all under the 

 microscope. In a hard-dried specimen they remind one of 

 the appearance of the grain in ivory. 



Under the microscope the different tissues present the 

 following characteristics : No. 1 is an epidermal and cortical 

 layer of the usual type ; under this is No. 2, consisting on the 

 outside of a meristem divided by periclinal walls. By means 

 of this the stem increases in thickness. Owing to unequi- 

 lateral growth of this layer, tissues (3) and (4) are rarely 

 central. Pitting is common in this part of the stem. The 

 meristem passes into a parenchyma, which constitutes the 

 greater bulk of the stem. Tissue (3) consists of cells which 

 are oblong in transverse section, but in longitudinal section 

 are seen to be many times longer than broad. They anasto- 

 mose occasionally. This tissue is penetrated by a number of 

 ducts — (?) mucilage -canals — about r^gi^- i^^ diameter, and 

 perhaps similar to those found in Macrocystis. The inner- 

 most tissue is hyphal in character, and, like the hyphge 

 of fungi, it does not stain with iodine and sulxahuric acid. (I 

 am not aware if this is a common characteristic amongst sea- 

 weeds). It contains " trumpet-hyphse," which give the usual 

 reactions for callus with chlor-zinc-iodine, Russow's callus 

 reagent, and corallin-soda. The last-mentioned stain, though 

 very distinctive, is, however, transient. With eosin the callus 

 stains rather more deeply than the rest of the tissue, but the 

 result is not very satisfactory. As will be seen, this is only 

 the fourth seaweed in which callus has been found. Oliver 

 says"''' that "in the Ncreocystis, as in Macrocystis, callus is 

 formed in the true sieve-tubes, as well as in the ' trumpet- 

 hyphae.' In the ' trumpet-hyphae ' of other LaminaricB I 

 have so far (with one exception) been unable to discover any 

 ■callus." The explanation of the figures illustrating Oliver's 



* " On the Obliteration of Sieve-tubes in Laviinaricc." — " Annals of 

 Botany," vol. i., p. 95. 



