device, from the Greek Ba@vug- deep, and 
TWay%)- a snare of trap. 
Size 
The first point to be considered is size. 
HARDY31! warns us against imagining that the 
rather frightening pictures sometimes repro- 
duced (without accompanying scale!) in the 
‘popular! press represent creatures of 
enormous size. In fact, most of the captured 
specimens average 2-3 inches in length, mea- 
surements of 10-12 inches and above being 
exceptional. On, the other hand, BEEBE with 
his bathysphere 6,29 and later observers in 
the bathyscaphes, consistently report much 
larger creatures - 10 feet or more in length 
20° It would seem that the larger fish and 
invertebrates have sufficient power and 
agility to evade the relatively cumbrous and 
slow-moving deep-sea nets. 
Direct observations have also tended to 
refute other long-established conventions 
concerning life in_the deep sea; such as its 
supposed scarcity3/, eed abundance 
with depth, and inactivityl®,1 920, 29,31, 
This should be remembered when designing 
apparatus for use in this region. 
It would therefore seem best to build 
the trap as large as can be conveniently 
handled by the available research vessel. 
Thermal Insulation and Flotation 
The need for some form of thermal insu- 
lation of the contents of the trap has 
already been mentioned. Obviously, those 
substances normally employed for this purpose 
would rapidly become saturated and ineffi- 
cient unless enclosed in a pressure-resistant 
housing. A material which does appear most 
suitable for this ee gS is gasoline 
gelled with ‘Napalm! 8,39, Prevention of 
convection currents reduces the thermal 
conductivity of this materiall0O to approxi- 
mately 3 x 10-4 cal.sec.-) cm™ per degree 
- comparable with the conductivities of 
cork, cloth and firebrick, and about three 
240 
times that of glass wool!1, js it is thixo- 
tropic and capable of flow!? the gel may be 
exposed to the hydrostatic pressure. 
Besides being inexpensive, another advan- 
tage of this gel is that its low specific 
gravity (ca-0.7) enables the insulating jacket 
to act as a float. Other greases and waxes 
(e.g. petrolatum) may bear a closer resemblance 
to the blubber of the whale, but are denser 
(S.G. ca 0.9) and cannot be gelled in situ in 
the cold. These and various microcrystalline 
waxes, polythene, etc. may be applicable where 
the apparent weight is not critical. 
Pressure Resistance 
So far, then, the apparatus is conceived 
as a fairly large chamber, constituting the 
live trap proper, surrounded by gelled gasoline 
to provide thermal insulation and flotation. 
To preserve the original hydrostatic pressure 
necessitates an excessively thick and heavy 
chamber if alloy steel be employed, but there 
is some possibility that filament-wound glass 
fibre-and-plastic vessels might serve above 
hadal depths. In the exploratory models it 
is proposed to allow water to escape through a 
valve to equalise pressures. Provided the rate 
of ascent is sufficiently slow,those species 
with well-developed swimbladders might be able 
to resorb sufficient gas to avoid permanent 
injury. 
Luminous Lures and Bait 
If the apparatus is to fulfil its inten- 
ded purpose within a reasonable period of time, 
it is presumably advisable to employ some form 
of lure or bait. The vicious circle resulting 
from the paucity of our knowledge of the habits 
and responses of these creatures can only be 
broken by an empirical choice of technique, 
based on the fragmentary observations which 
have been made of those fish surviving for up 
to thirty-six hours Luminescence being one 
of the most obvious characteristics of the 
deep-sea fauna, it must surely serve some pur- 
pose in attraction of mates or prey. BEEBE/3 
records that a Pacific myctophid (lantern-fish) 
reacted to the intermittent exposure of a lumi- 
nous wrist watch, but was unaffected by the 
much stronger beam of a flashlight. MARSHALL 26 
