17.] CHAPTER IT. SPECIAL MORPHOLOGY OF THE MEMBERS. 83 



(6) The Gametangia. The general morphology of the gametangia 

 is very much the same as that of the sporangia. 



With regard to the terminology employed in designating these 

 organs, they are said to be male when they contain protoplasm 

 which is capable of effecting fertilisation ; and female, when they 

 contain protoplasm capable of being fertilised. When there is no 

 external indication of the physiological nature of the organ, it 

 is simply termed a gametangium. But when the male and female 

 organs respectively are clearly differentiated, special names are 

 given to them in order to indicate peculiarities in their structure 

 or function, or the group of plants to which they belong. In 

 the first place a distinction must be drawn, in the case of these 

 differentiated gametangia, between those which give rise to clearly 

 differentiated gametes, and those the protoplasm of which does not 

 undergo such differentiation. To the former category belongs 

 the male organ, termed antheridium, in which spermatozoids are 

 developed, and the female organs, termed oogonium or archegonium, 

 in which one or more oospheres are differentiated. To the latter 

 category belong the male organ termed pollinodlum {e.g. in 

 Peronosporeas and some Ascomycetes), and the female organs 

 termed procarp (Florideae) or archicarp (Ascomycetous Fungi). 



In the lowest plants in which the sexual formation of spores 

 takes place, the whole cell, when the organism is unicellular, or 

 any cell, when the organism is multicellular, becomes a game- 

 tangium, without being specially modified for the purpose. This 

 is the case, not only in isogamous plants {e.g. Paudorina, Ulothrix, 

 Conjugate), but in some heterogamous plants {e.g. Sphseroplea) 

 in which the gametes are perfectly differentiated into spermato- 

 zoids and oospheres. 



In plants of higher organisation there are specialised game- 

 tangia. In the simpler forms of these the male and female 

 gametangia are externally similar, as in the Volvocinene, Ecto- 

 carpus, and Cutleria, among the Algse, and in the Zygomycetes 

 and some Ascomycetes {e.g. Eremascus) among the Fungi. In the 

 more complex forms, the male and female gametangia are dis- 

 similar. 



The undifferentiated gametangia are generally unicellular and 

 unilocular; but they are multicellular and multilocular, in some 

 Phseosporese {e.g. Ectocarpus, Giraudia, Scytosiphon, Cutleria). 



The differentiated gametangia are of various structure. The 

 antheridium is unicellular in most of the lower plants (Green 



