An introduction to the study of seaweeds / by George Murray.

  • Murray, George (George Robert Milne), 1858-
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to the study of seaweeds / by George Murray. Source: Wellcome Collection.

    41/324 (page 23)
    strand, the mostly highly developed element of the latter being the sieve-tubes found in Macrocystis (Laminariacecv). The sculpturing of outward form reaches its highest point in the differentiation (1) of a root-like holdfast, which, however, is not an organ of absorption unless possibly in the case of certain partially parasitic forms (cf. Notheia, Choreocolax, Figs. 5rf, 64); (2) of a stem and (3) of leaf-like appen- dages. From this type there are varying intermediate forms down to the wholly undifferentiated type, which occurs among both multicellular and unicellular forms. These intermediate forms may be placed into two categories—those exhibiting a root-like differentiation from an otherwise unspecialised body, and those in which there is merely a distinction between base and apex. In some of the lower multicellular Algae all the cells are alike, and equally capable of vegetative and reproductive functions. Among the unicellular forms there are those which exist free singly, and others united into a kind of spurious tissue or colony by a common investing mucilaginous cell-wall, and occurring either in rows or filaments, or in more or less indefinite masses. The highest development attained by the unicellular forms, if they may be so termed in this connection, is to be found in the multinucleate group of Siphonece, which includes many forms with differen- tiated root-like appendages and leaf-like shoots, and others in which the specialisation is carried so far as to represent leaf-like, stem-like, and root-like organs. Growth in length is either (1) apical, and effected