GENERAL INTRODUCTION
25
selveS by
"
spores
”
instead of seeds produced by owers;
We may divide them into two types, xed and driftin‘g.
The former are the sea weeds and may be further divided
into four groups each of which has‘a characteristic colour
as well as structure.
There are (1) Blue—green Algæ (Cyano’
phyceæ), (2) the Green Algæ (Chlorophyc'e‘æ), (3) the Brown
’
Algæ (Phæophyceæ), and (4) the Red Algæ (Rhodophyceæ) ;
these are found from high—water mark downward into deep
water in the order named, ; this is discussed. in more detail
later.
The rst—named are of slight importance, they are
minute plants which sometimes form a slimy lm over rocks,
but many of the others are of considerable size, the Brown
Algæ including, not only the strange oating Sargassum
weed which gives its name to the Sargasso Sea in the Gulf of
Mexico, but also the largest known plant in M acrooystis
pyrifem, with… fronds 200
_
yards long "which is found'off
the southern parts of South America.
Since plants demand
'
a certain minimum of light, all trace of weed disappears
from the bed of the ocean below a certain depth.
The deepest water from which weeds have been taken with any‘cer-tainty that they were actually growing on the bott0m
appears
to be about 60 fathoms, but-normally they are not
found abundantly except in sha‘llow water;
_
î
drifting plant life, apart from the large Sargassum
cOnsists of minute single—celled plants called
which have tiny
and.also the Peridinians which,
as
stated
above, can be cOnsidered either plants - or
animals as they have certaineharacteristié$ of both.
Both
-
occur in untold billions andare of primary importance in
the
of marine life.
,
'
25
selveS by
"
spores
”
instead of seeds produced by owers;
We may divide them into two types, xed and driftin‘g.
The former are the sea weeds and may be further divided
into four groups each of which has‘a characteristic colour
as well as structure.
There are (1) Blue—green Algæ (Cyano’
phyceæ), (2) the Green Algæ (Chlorophyc'e‘æ), (3) the Brown
’
Algæ (Phæophyceæ), and (4) the Red Algæ (Rhodophyceæ) ;
these are found from high—water mark downward into deep
water in the order named, ; this is discussed. in more detail
later.
The rst—named are of slight importance, they are
minute plants which sometimes form a slimy lm over rocks,
but many of the others are of considerable size, the Brown
Algæ including, not only the strange oating Sargassum
weed which gives its name to the Sargasso Sea in the Gulf of
Mexico, but also the largest known plant in M acrooystis
pyrifem, with… fronds 200
_
yards long "which is found'off
the southern parts of South America.
Since plants demand
'
a certain minimum of light, all trace of weed disappears
from the bed of the ocean below a certain depth.
The deepest water from which weeds have been taken with any‘cer-tainty that they were actually growing on the bott0m
appears
to be about 60 fathoms, but-normally they are not
found abundantly except in sha‘llow water;
_
î
drifting plant life, apart from the large Sargassum
cOnsists of minute single—celled plants called
which have tiny
and.also the Peridinians which,
as
stated
above, can be cOnsidered either plants - or
animals as they have certaineharacteristié$ of both.
Both
-
occur in untold billions andare of primary importance in
the
of marine life.
,
'