SECT. I CRYPTOGAMS 331 



therefore be termed SPORE plants, and Phanerogams seed plants or 

 Spermaphy tes ; although previous usage and custom would recommend 

 adherence to the older terms. 



The Cryptogams are divided into the following main groups : — 



I. The Thallophyta, embracing a great variety of plants whose 

 vegetative portion may consist of one or many cells in the form of a 

 more or less branched thallus. Reproduction is both sexual and 

 asexual, but there is usually no definite succession of the two modes 

 of reproduction. 



II. The Archegoniatae exhibit a regular alternation of two 

 generations in their life -history. The asexual generation forms 

 spores, and is called the Sporophyte. From the spore the sexual 

 generation or Gametophyte develops ; this bears sexual organs of 

 characteristic construction, tlie male organs being called antheridia, 

 and the female organs archegonia. From the egg-cell contained in 

 the latter, after fertilisation, the sporophyte again arises. The 

 Archegoniatae are divided into 



1. The Bryophyta, which include forms with a leaf-like thallus, 

 as well as cormophytic forms, with evident segmentation into stems 

 and leaves. The Bryophytes possess no true roots, and their con- 

 ducting bundles, when present, are of the simplest structure. The 

 sporophyte is a stalked or unstalked capsule, which lives semi- 

 parasitically on the sexual plant. 



2. The Pteridophyta have small thalloid gametophytes ; the 

 sporophytes exhibit a segmentation into stems, leaves, and roots, and 

 also possess true vascular bundles ; they thus resemble the Phanero- 

 gams in structure. 



The Thallophytes and Bryophytes are also characterised as Cellular Plants, in 

 contrast to the Pteridophytes or Vascular Cryptogams, which, together with the 

 Phanerogams, are collectively designated Vascular Plants. Bryophyta and Pteri- 

 dophyta must be regarded as having had a common origin from the higher Algae, 

 the development of the two groups having been on different lines. 



I. THALLOPHYTA 



It was formerly customary to divide the Thallophyta into 

 Algae, Fungi, and Lichens. The Algae are Thallophytes which 

 possess chromatophores with pigments, particularly chlorophyll ; 

 they are, therefore, capable of assimilating and providing inde- 

 pendently for their own nutrition. The Fungi, on the other hand, 

 are colourless and have a saprophytic or parasitic mode of life. 

 Such a method of classification, however, although possessing a 

 physiological value, has no phylogenetic significance, as it does not 

 express the natural relationships between the various groups. In 

 the Lichens (Lichenes), whi.;h were formerly regarded as simple 

 organisms, the thallus afi"ords an instance of a symbiosis of Algae 



