INTRODUCTION 19 
is in its infancy, and many other types no doubt 
await discovery. A recent estimate of the bulk of 
this flora compares the inconspicuous marine or- 
ganisms of the Sargasso Sea with the bulk of the 
floating banks of gulf-weed that give this great tract 
of ocean its name, with the result that the micro- 
scopic forms enormously exceed the gulf-weed in 
aggregate mass. The result is all the more striking 
since it is known that the Sargasso Sea is poor in 
these minute forms compared with many other 
regions of the ocean. As regards the Sargassa float- 
ing free in this region and elsewhere, the view 
generally adopted accounts for their presence by 
the supposition that they have been torn from their 
natural moorings and drifted by currents, and that 
they slowly perish in the Sargasso Sea, to be renewed 
by fresh supplies from the same source. The theory 
has much to recommend it on purely oceanographical 
grounds, but the difficulty remains that Sargassum 
baceiferum, which composes the mass of free-float- 
ing Sargasse in the tropical Atlantic, has never 
been recorded as growing attached, in a quantity 
sufficient to account for the supply. Moreover, other 
Sargassa do grow attached in enormous quantities, 
but they are of only casual occurrence in a free state. 
There is still the refuge that S. bacctferwm is a mere 
“srowth-form” modified by passage down currents. 
This, however, has no farther observation to support 
it, and, moreover, an examination of Sargassa from 
the centre of this still region of the ocean shows no 
symptom of recovery of broader fronds after removal 
from the influence of the currents that bound it. 
c 2 
