DREDGING ORDISES. 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 oi 

 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. 



