■*-o 



>■% 



\ 1 



T^^ 



Carpo- 

 sporophytes 



Falkenbergia 

 (haploid tetrasporophyte) 



\ — 1 



■^O 



^'^ 



^o 



Fig. 126 Asparagopsis armata. Top left, apical portion of thallus; 



right, transverse section showing original main axis in centre 



(after Kylin) : diagram of life cycle of Asparagopsis armata. 



iaceae except Asparagopsis, the thallus is flattened and the appen- 

 dages are arranged in two rows. The principal interest of this genus 

 Ues in its remarkable Ufe history. In A. armata reduction division 

 appears to take place at germination of the zygote and the haploid 

 carpospores which result give rise to an entirely different genera- 

 tion that has formerly been knovm as Falkenbergia rufo-lanosa. 

 Although the Falkenbergia plants are haploid they give rise to 

 tetraspores but without meiosis taking place. From these tetraspores 

 new plants of A. armata are presumably produced. At the first 

 divison of the zygote two nuclei of the tetrad formed degenerate 

 and the remaining two are of the same sex. There must therefore 

 genetically be at least two types of female plant. The life cycle is 

 represented in Fig. 126, and the situation must be regarded as 

 quite atypical, though similar life cycles appear to exist in Bonne- 

 maisonia asparagoides and its small asexual plant, Hymenoclonium 



230 



