EUPHYCOPHYTA 



251 



to give a large fusion cell. The diploid nucleus divides many times 

 and the daughter nuclei each pass into lobes that are budded off 

 from the fusion cell. Each lobe gives rise to a short gonimoblast 

 filament, the terminal cell of which produces a pear-shaped carpo- 

 spore, whilst the subterminal cell gives rise to a new^ two-celled 

 carpospore branch. In this way numerous carpospores are pro- 

 duced. 



The wall of the cystocarp is two-layered, the inner wall being 

 formed directly by cells derived from pericentral cells. The cells of 

 the inner wall divide tangentially to give the cells that form the outer 

 wall, so that ultimately both layers have come from the pericentral 

 cells. The tetrasporangia, which develop from pericentral cells, 

 develop in the apical portion of branches, and as they are protected 

 by being embedded in the thallus, the branch is usually much 

 swollen and distorted. The genus is widespread in cold and warm 

 waters and the species particularly frequent rock pools. 



Fig 142 Janczewskia. A, J. moriformis on Chondria sp. ( x 6). 



B, filaments of J. lappacea in host, Chondria nidifica ( x 180). C, 



longitudinal section of cystocarp of J. moriformis ( x 180). D, 



antheridial conceptacle of J. lappacea ( x 180). (After Setchell.) 



