2 CLASSIFICATION OF THE VEGETABLE KINGDOM. 



bundles. The lowest Mosses have, however, a thallus. Fertili- 

 sation is accomplished by means of self-motile, spirally coiled 

 spermatozoids, through the agency of water. From the fertilised 

 oosphere a " fruit-body " (capsule) with unicellular organs of 

 reproduction (spores) is produced. The spore on germination 

 gives rise to the vegetative system, which bears the organs of 

 sexual reproduction ; and this system is divided into two stages 

 the protonema, and the leaf-bearing plant produced on it. 

 Alternation of generations : 



I. The protonema and the entire nutritive system which 



bears the organs of sexual reproduction. 

 II. The capsule-like sporangium, with spores. 



2 Classes : 1. Hepatica?, Liverworts. 



2. Musci, Leafy Mosses. 



Division III. Pteridophyta or Vascular Cryptogams, 

 Fern -like Plants having- leaf-bearing shoots, true roots, and 

 vascular bundles with tracheides and sieve-tubes. Fertilisation 

 as in the Mosses. From the fertilised oosphere the leaf -bearing 

 shoot arises, which bears on its leaves the reproductive organs, 

 the spores, in capsule-like sporangia. From the germination of 

 the spore a small prothallium is formed, which bears the sexual 

 reproductive organs. 



Alternation of generations : 



I. Prothallium with organs of sexual reproduction. 

 II. Leaf-bearing shoot with capsule-like sporangia. 



3 Classes: 1. FilicinaB, True Ferns. 



2. Equisetina?, Horsetails. 



3. Lycopodinse, Club-mosses. 



Division IV. Gymnospermae. The vegetative organs are in 

 the main similar to those in the 3rd Division ; special shoots are 

 modified into flowers for the service of reproduction. From the 

 oosphere, which is fertilised by means of the pollen-tube, the 

 leaf -bearing plant is derived; this passes the first period of its 

 life as an embryo in the seed, and continues its development when 

 the germination of the seed takes place. The organs correspond- 

 ing to the spores of the two preceding Divisions, are called respec- 

 tively the pollen-grain and embryo-sac. The pollen-grains are 

 multicellular ; i.e. they contain an indistinct prothallium. In the 

 embryo-sac a prothallium, rich in reserve material (endosperm), 



