CHAP. VI.] DEEP-SEA DREDGING. 261 



water. It is of great importance not to give any- 

 rotatory motion to the sieves in this part of the 

 process, for such is very ruinous to fragile organisms. 

 The sieves should he gently churned up and down, 

 whether singly or together. The result, of course, is 

 that the rougher stones and gravel and the larger 

 organisms are washed and retained in the upper 

 sieve. The fine mud or sand passes through the 

 whole of the sieves and subsides into the bottom of 

 the tub, while the three remaining sieves contain, in 

 graduated series, the objects of intermediate size. 

 The sieves are examined carefully in succession, and 

 the organisms which they contain gently removed 

 with a pair of brass or bone forceps into the jars 

 of sea-water, or placed at once in bottles of weak 

 spirit of wine. 



The scientific value of a dredging operation de- 

 pends mainly upon two things, — the care with which 

 the objects procured are preserved and labelled for 

 future identification and reference, and the accuracy 

 with which all the circumstances of the dredging, 

 position, depth, nature of ground, bottom tempera- 

 ture, date, &c., are recorded. With regard to the 

 preservation of the animals, I cannot here go into 

 detail. There are many ways of preserving, special 

 to the different invertebrate groups ; and ' taxidermy ' 

 is in itself a complicated art. I will merely men- 

 tion one or two general points, A specimen in 

 almost every group is of infinitely greater scientific 

 value if it be preserved entire with its soft parts. 

 For this purpose the most usual plan is to place it 

 at once in spirit of wine diluted to about proof. 

 Care must be taken not to put too many specimens 



