490 



LIFE-HISTORIES 



into a new Nemalion plant. Spores which are thus the indirect 

 product of fertihzation are called carposporesA 



Sexual reproduction in Chondrus (Fig. 118) as also in almost all 

 of the Rhodophycese is by means of carpospores. The process is 

 often much more indirect and complicated than in Nemalion; and, 

 as is the case with Chondrus, the details may be somewhat modified 



Fig. 320. — Thread-weed {Nonalion multifidum. Thread-weed Family, 

 Helminthocladiacea;). I, branch bearing male gametangia (sp), and a 

 female gametangium with swollen base (c) and slender neck (<)• II. a 

 female branch after fertilization, the neck (0 withered, and the base 

 beginning to divide for the formation of branches. III-V, later stages 

 in the formation of branches which finally bear spores. All much 

 magnified. (Thuret and Bornet.) — A brownish-red seaweed with 

 branches .5-20 cm. long, on exposed rocks at low-water mark, North 

 Atlantic coast. 



by formation of the carpospores Avithin the thallus, as shown in 

 Fig. 321. Non-sexual reproduction is accomplished very generally 

 throughout the class by non-motile spores, which are produced 

 usually four in a sporangium. The sporangia may be either at the 

 surface or embedded within the thallus as m Chondrus. 



The thallus in this genus, as with a large part of the class, 

 exhibits a differentiation of cells similar to that already 



^ Carp'o-sporc < Gr. karpos, fruit. 



