1869.] on the Scientific Exploration of the Deep Sea. 



415 



firmed by the elaborate analyses of Dr. Frankland (Appendix II.), of indi- 

 cating the universal presence of a highly Nitrogenous substance, such as 

 may well be supposed to afford a direct supply of nutritive material to the 

 Rhizopodic Fauna (Sponges and Foraminifera, with Bathybius ?) of the 

 Ocean-bottom, as was first suggested by Prof. Wyville Thomson in his 

 Memoir on Iloltenia*. 



24. For the management of the Dredging-operations two Assistants were 

 appointed on the recommendation of Mr. Gwvn Jeffreys, under whom 

 both of them had previously worked : Mr. Laughrin of Polperro, an old 

 Coastguard-man, and an Associate of the Linnean Society, for dredging 

 and sifting ; and Mr. B. S. Dodd for picking out, cleaning, and storing the 

 specimens collected. Both did their respective shares of the work care- 

 fully and zealously. 



25. The Sieves were constructed under the direction of Mr. Jeffreys. 

 These were five in number, and were "nested" or fitted one within an- 

 other, with a strong handle of galvanized iron affixed to the bottom sieve 

 on each side ; so that the dredged material might pass through all the 

 sieves at the same time, as they were worked in a large tub of sea-water on 

 the deck. Their frames were of oak ; and their lining was of copper 

 wove-wire, the mesh of the top sieve being 2 holes to an inch, that of 

 the next 4 holes, and of the succeeding sieves 8, 16, and 32. Each sieve 

 was furnished with a beading round the inside rim, to prevent specimens 

 remaining under the edges when the sieves were washed after each dredging ; 

 the risk of intermixture of specimens obtained from different dredgings 

 was thus avoided. 



26. Two other kinds of Sieve were also found useful. — One was spherical, 

 with a lid fastened inside by bolts ; its frame consisted of a strong net- 

 work of copper ribs, which was lined with very fine wire-gauze of the same 

 metal, and it had a ring through which a line would pass. Its use was 

 to sift and wash away in the sea the impalpable mud got in large quanti- 

 ties at great depths ; so as to leave only for examination all organisms 

 exceeding in size l-36th of an inch, this being the diameter of the 

 mesh in the wire-lining. Some of the residuum or strained mud was 

 likewise preserved, after sifting the material in the usual way. This con- 

 trivance, which we called the "globe-sieve," saved a great deal of the 

 time and useless labour expended in washing dredged material of that 

 viscid kind through the ordinary sieves in a tub of sea-water, which soon 

 becomes so turbid, that unless the tub is continually emptied and refilled 

 it is extremely difficult (if possible) to detect any specimens. — Another 

 kind of sieve had a similar framework ; but the body was semiglobose, with 

 an open funnel-shaped neck. It was fastened to a long pole, and served 

 for catching Pteropods, Salpce, and other animals on the surface of the 

 sea. This went by the name of the " scoop-sieve." 



27. An ample supply of spirit, jars, and bottles was provided; and the 



* Philosophical Transactions, 1869, p. 801. 



2 k 2 



