DEEP-SEA LAMPS 
57 
important facts of this great mass of literature in such 
a form as may interest those who do not possess a 
specialist’s knowledge.” The main conclusions are 
clearly presented with examples and excellent illus- 
trations^ in number sufficient to convince without 
bewildering. On one point we could desire a little 
more information. There is no suggestion of the 
means by which creatures differing so little in bodily 
frame and tissue from the shallow-water species, from 
which they are apparently derived by migration into 
the deeps, support the enormous pressure in their 
present home. Some explanation seems to be required, 
though an incident in the recent erection of the Forth 
Bridge seems to suggest that the modification of 
tissue to endure high pressure may be acquired more 
rapidly than is supposed. The men employed in the 
steel shells or caissons sunk to form the foundations 
of the piers, worked in a pressure of air rather greater 
than the pressure of the water outside, which would 
otherwise have penetrated between the rims of the 
caissons and the ground. On those days on which 
they were not employed, and came to the surface, 
they felt such pain in the joints from the expansion 
of the air, which had been absorbed at high pressure, 
that they begged to be allowed to go down into the 
caissons and spend their off hours in the pressure to 
which they had grown accustomed. This instance of 
partial migration into conditions of high pressure, 
seems worthy of a place among the facts of deep-sea 
exploration. Yet it must remain among the strangest 
