CHAP. X.] CONTINUITY OF THE CHALK. 497 
chalk element is of no more importance than is the 
original British element in our own English people.” 
Mr. Prestwich thus fully admits the high pro- 
bability of the ‘ continuity’ for which we contend. 
The last question which he raises in the sentence 
quoted is one of enormous difficulty, which we have 
as yet no data to solve. It is perhaps not very much 
harder, however, after all, than the problem in ethno- 
logy which he has selected as an illustration. 
Several other very important questions bearing 
upon the conditions of the ocean at great depths, 
occupied the attention of the naturalists in scientific 
charge of the dredging cruises of the ‘ Lightning’ 
and ‘ Porcupine.’ An assistant versed in the methods 
of chemical and physical research accompanied the 
vessel on each occasion. A son of Dr. Carpenter, 
Mr. William Lant Carpenter, B.A., B.Sc., went on 
the first cruise with Mr. Jeffreys. Mr. John Hunter, 
F.C.S., a promising young chemist, since deceased, 
accompanied me to the Bay of Biscay, and Mr. Her- 
bert Carpenter, a younger son of my colleague, was 
our companion during the third long cruise in the 
Froe channel. 
The specific gravity of the water was taken at 
each station, and in the serial soundings the water- 
bottle was let down to the intermediate depths and 
the water carefully tested. The differences observed 
were very slight, but they were as a rule confirmatory 
of Professor Forschammer’s opinion that Arctic water 
contains less salt than the sea-water of temperate 
and intertropical regions. 
As I have already mentioned (page 46), organic 
matter in appreciable quantity was detected by the 
K K 
