230 



MANUAL OF BOTANY 



open, but when the spermatium comes into contact with the 

 trichogyne, the parts of the cell-walls which are touching 

 become absorbed, and the contents of the spermatium pass into 

 the procarp through the opening. A somewhat similar arrange- 

 ment is described for certain- of the Fungi, where it is called an 

 archicarp. 



The position of the gametangia varies in different plants ; in 

 some they may occur on any part of the plant body, which gives 

 no indication of special diiferentiation with a view to their 

 occurrence ; in others, particularly those where the gametophyte 



Fig. 497. 



Fis. 498. 



Fig. 497. Archegouium of a Lirerwort {Mar- 

 i'haniia). n. Keck. oos. Oospliere. a. An- 



therozoids. Fig. 498. Procarp of one of the 



Red Seaweeds, tr. Trichogyne. sp. Sper- 

 matia. After Kny. 



shows complexity of structure, they are confined to particular 

 portions which are modified in a way which suggests the sporo- 

 phore or inflorescence of the differentiated sporophyte. The 

 greatest specialisation is shown in the group of the thalloid 

 Liverworts (figs. 499 and 500), where both antheridia and 

 archegonia are borne upon special erect branches of the thallus. 

 These differ in form : the antheridial receptacle is a body with 

 a flattened head, on the upper surface of which the antheridia 

 are placed in narrow pit-like depressions ; the archegonia occur 

 on the under side of a similar vertical receptacle, which shows 



