Helmmthocladie(v 



39 



Chantransia were merely non-sexual stages of Batrachospermum, 

 and that under brighter condi- 

 tions of light they underwent a 

 metamorphosis, giving rise to 

 the sexual stage or Batracho- 

 spermum. The carpospores of 

 the latter genus develop a pro- 

 tonema-like growth which bears 

 great resemblance to species of 

 Chantransia, and many of these 

 growths, both of Batrachosper- 

 mum and Lemanea, have been 

 erroneously described as species 

 of that genus ; but, at the same 

 time, these have nothing to do 

 with the valid genus Chantransia. 

 The sexual reproduction of Chan- 

 transia has only been fully worked 

 out in one species Ch. corym- 

 bifera Thur. On the fertilization 

 of the carpogonium it develops 

 numerous gonimoblasts upward- 

 ly and on one side. There is thus 

 formed a naked corymbose cysto- 

 carp, the terminal cells of the 

 gonimoblasts producing the car- 

 pospores. The antheridia are 

 likewise developed in clusters. 

 Asexual reproduction occurs by 

 tetraspores and also by other 

 spores which remain undivided 

 and are known as ' monospores.' 

 These, on germination, divide 

 into four cells in one plane, 

 giving rise to the basal stratum 

 from which the branched fila- 

 ments spring. 



There are some seven or eight British freshwater species of the genus, of 

 which Ch. pygmcea Kiitz. (fig. 2 A C) and Ch. molacea Kiitz. are perhaps the 

 most frequent. 



Fig. 2. A, Chantransia pygmaa 

 Kiitz., from Penyghent, W. Yorks. 

 ( x 100). B and C, branches of the 

 same with 'monospores' (m) ( x 300). 

 D, Ch. scotica Kiitz., from Cornwall; a 

 small portion of the thallus showing 

 the pits in the transverse walls ( x 400). 



