Marine Groves and Gardens 131 



as they attain their full growth within a year. One of 

 these is reported as having a stem of the thickness ot 

 a clothesline and reaching the length of nine hundred 

 feet; along the greater part of this ropelike stem are 

 attached numerous expansive "leaves." Another, the 

 bladder wrack, has a stem the length of which measures 

 a hundred and fifty feet. But, although its stem is 

 relatively short, it is distinctive in having at the end 

 a great globular float bearing leaflike appendages over 

 twelve feet long. 



Except for those low, invisible, fungous forms, the 

 bacteria, marine vegetation is entirely restricted to the 

 surface of the sea and its shallow waters. This limi- 

 tation is obviously far short of that of the animals, 

 who, as will be revealed in a later chapter, range to 

 the greatest known depths. Now the reason for this 

 restriction would not be hard to guess, even though 

 our knowledge of conditions generally regulating the 

 growth of plants on the sea floor were ever so imper- 

 fect. The chief factor, of course, is light; for the sea- 

 weeds are no more able than are their land relations 

 to live beyond the reach of the sun's rays. The amount 

 of light that penetrates the sea rapidly diminishes with 

 increasing depth ; therefore, few living plants are 

 found much lower than a hundred and fifty feet. 



Yet even at this level they do not sensibly decrease 

 in numbers. They are, however, greatly reduced in 

 size. Nor is this the only change. They are exten- 

 sively altered in character. In fact, it is here in these 

 remote regions, where filter feebly the last remaining 

 rays of light, that flourish the most varied, the most 

 colorful, the most exquisitely delicate and, in many 



