28 
POPULAR SCIENCE REVIEW. 
by nautical people — a soft mealy substance, having the appear- 
ance of mud but of very close texture. This substance is de- 
scribed as remarkably sticky, having been found to adhere to 
the sounding rod and line through its passage from the bottom 
to the surface, in some instances more than 2,000 fathoms. 
When a little of this mud is taken out and thoroughly dried it 
becomes white or reddish-white and (though less white) it 
closely resembles very fine chalk.* Fully nine-tenths by 
weight of this deposit was estimated by Professor Huxley to 
consist of minute skeletons of Foraminifera, composed of car- 
bonate of lime. Examined under the microscope it presents a 
vast multitude of exceedingly minute granules and fragments, 
and a certain proportion of some clear mineral, perhaps quartz, 
perhaps volcanic sand. The granules and fragments are almost 
without exception referable to one species of Foraminifera 
known as Globigerina, traced through a complete series of 
gradations from less than one-thousandth of an inch in diameter 
(when it consists of one or two cells) to more than one-sixtieth 
of an inch. The general appearance of the complex forms 
consisting of several cells is given in the plate annexed. 
Among the mud that does not consist of fragments of Globi- 
gerinae are fragments of diatoms and indications of sponges. 
When these remains were first found to form a large part of the 
mud in depths of upwards of 2,000 fathoms, and it became 
clear that they were uniformly spread over a large space, the 
knowledge of the existence of animal life in deep water was so 
small that many naturalists speculated as to the possibility that 
the accumulation consisted only of the skeletons — the animals 
themselves having lived near the surface. Subsequent obser- 
vations have shown that there is no known limit of depth at 
which animal life ceases. There can hardly be a doubt that 
the Globigerinae are the natural inhabitants of the ocean floor 
at all depths under favourable conditions, and that these con- 
ditions consist of a warm, or comparatively warm, sea bottom. 
It is also certain that a warm sea bottom is a local condition 
nearly independent of latitude — absent in some seas whose 
surface water is very warm, and present in others where the 
surface and moderate depths are very cold. 
In the dredging expedition of 1868, a large quantity of 
Globigerina mud was lifted always from the deep warm bottoms ; 
but this mud was found to include animal life of higher types 
and was everywhere permeated by a peculiar glairy organic 
substance, regarded by Prof. Huxley as an intermediate condition 
between plant and animal life, and called by him Bathybius. 
The nature and true position of this remarkable substance is not 
* Huxley’s Appendix to Capt. Dayman's account of Deep-Sea Soundinys in 
1I.M.S. Cyclops. 
