PRINCIPAL GROUPS OF PLANTS. 



33 



and dews. It shows, however, all the morphological structure of 

 the growing plant. 



Fig. i6. Chondrus crispus: A, B, C, D, various forms of thallus; H, hold-fast; F, 

 sporangia; T, transverse section of thallus showing epidermis (E), sporangium with spores 

 (F); S, spores separated in glycerin preparation of thallus by pressure on the cover-glass. 

 The spores occur in groups of four (tetraspores) and the tetrad group is about 30M in diameter. 



In a closely related genus, Gigartina (Fig. 17), which is found 

 in imported Chondrus, the fruit bodies occur in numerous cylindri- 



3 



