DREDGING CRUISES. 417 
there was no absolute certainty that the animals entangled on 
the sounding instrument had actually come up from the bottom. 
They might have been caught on the way. 
But now all doubt was removed. A submarine cable lies on 
the ground throughout its whole length. Before laying it, its 
course is carefully surveyed and the real depth accurately ascer- 
tained. Fishing it up is a delicate and difficult operation, and 
during its progress the depth is checked again and again. 
When, therefore, as in this case, the animals dragged up with 
a cable from depths of upwards of one thousand fathoms are 
found, not sticking loosely to it, but moulded upon its outer 
surface, or cemented to it by horny or calcareous excretions, it 
is evident that they must have lived and grown upon it at the 
bottom of the deep sea. 
The subsequent dredging cruises of H.M.SS. “ Porcupine” 
and “ Lightning ” in 1868, 1869, and 1870, under the scientific 
direction of Dr. Carpenter, Professor Wyville Thomson, and Mr. 
Gwyn Jeffreys, afforded additional and convincing proofs that 
life abounds in the abyssal regions of the ocean. During these 
several cruises 57 hauls of the dredge were taken at depths 
beyond 500 fathoms, and 16 at depths beyond 1,000 fathoms, 
and in all cases life was abundant. In 1869 two casts were 
taken in depths greater than 2,000 fathoms, and proved equally 
successful in bringing up specimens of deep-sea life. With the 
deepest cast, 2,435 fathoms, off the mouth of the Bay ot 
Biscay, living, well-marked, and characteristic specimens of all 
the five invertebrate sub-kingdoms were taken. ‘“ And thus,” 
says Professor Wyville Thomson,* “the question of the existence 
of abundant animal life at the bottom of the sea has been 
finally settled, and for all depths, for there is no reason to 
suppose that the depth anywhere exceeds between three and 
four thousand fathoms; and if there be nothing in the con- 
ditions of a depth of 2,500 fathoms to prevent the full 
development of a varied fauna, it is impossible to suppose 
that even an additional 1,000 fathoms would make any great 
difference.” 
It may be asked how the deep-sea animals bear the enormous 
pressure at these great depths, which seems at first sight alone 
* The Depths of the Sea. London, 1873. 
