1913] YAMANOUCHI—ZANARDINIA 29 
margin. The latter form is similar to the Zanardinia plant occur- 
ring in nature. 
In Zanardinia plants as they occur in nature, therefore, the 
« and 2% generations have similar outer morphological characters. 
When young, no distinction can be seen, but when the plants 
become mature, some individuals produce only gametangia, and 
others only zoosporangia. The cytological study has now shown 
that the gamete-bearing plant has 22 chromosomes and the zoospore- 
bearing plant double the number, and also that the product of the 
gamete-bearing plant establishes the Zanardinia plant with 44 
chromosomes, identical with the gamete-bearing plants as found 
in nature. Therefore it is certain that the Zanardinia plants in 
nature which have 44 chromosomes and produce zoosporangia 
come from the fertilized gametes, and the plants in nature which 
have 22 chromosomes and produce gametangia come from the 
zoospores. These two kinds of Zanardinia plants are not homolo- 
gous in character, but fundamentally different from each other, 
and in the life cycle alternate with each other. 
Zanardinia plants in the Bay of Naples grow all the year around. 
The formation of gametes and zoospores is restricted to a certain 
season of the year. From October to December, the plants are near 
the adult stage, but few are in reproductive stages, so that from 
their appearance it is impossible to determine whether they are 
gametophytes or sporophytes. From early in January to the 
middle of February, the plants with zoosporangia are abundant, 
and this season is the climax period of zoospore formation. Toward 
the end of February and during March, the gametangia-bearing 
plants are abundant, and this is the season of gamete formation. 
Then both kinds of adult plants cease to form reproductive organs 
but may continue to live as perennials with no remnant of repro- 
ductive organs. From February to April young sporelings are 
found and then gradually the larger cups appear. From May 
till October, the young plants, the product of both gametes and 
Zoospores, grow and attain nearly the adult size in late autumn. 
It seems evident that zoospores are produced early in the season, 
in January and F ebruary, and that they germinate at once. The 
production of gametes is a little delayed and the fertilized gametes 
