* KNOWLEDGE 



(July 6, 1883 



THE FISHERIES EXHIBITION. 



NATUEAL UISTORY DEPARTMENTS. 

 By Joun Ernest Ady. 



II. (continued). 



"TTTE now pass on to consider the relation of the 

 \V minute organisms considered in our last article, 

 to the important formations wliicli have and are still 

 taking place in the hed of the deep sea, and on which 

 so much light has recently been thrown by the late Sir 

 Wyville Thomson, and his associates of the Chalknr/fr 

 expedition. If a piece of chalk, such as that of Graves- 

 end, be gently powdered in a mortar, the uiass tied up in 

 a small bag of coarse calico, and kneaded thoroughly in a 

 large bowl of fresh water until it has been reduced to 

 about one-fourth of its bulk, a milky fluid with an appre- 

 ciable deposit will result ; the supernatant liquor may be 

 poured off, and the residue thoroughly well washed in a 

 large test-tube, and allowed to settle. This operation 

 should be repeated several times, after which it will be 

 found that the deposit consists almost entirely of the tests 

 of ForaminiJ'tra mi.xed with a variety of things, such as 

 sponge and other spicules, &c. Conspicuous amongst the 

 Foraminifera two beautiful forms may be recognised ; these 

 are Globigerbia and Texlidaria. 



Fig. 3. — Globigerixa Ooze, floor of the Atlantic Ocean, x 65. 

 g. Glohigerina buUoides ; o. Fragments of Orhulina universa ; 

 n. Nautiloid Foraminifera ; 7i. Haliomma, one of the Polycystina 

 {Original). 



As long ago as 1865-1866 Major Owen read two papers 

 to the Linna?an Society, descriptive of the life-habits of 

 Glohigeriiia and other forms, which he obtained from the 

 surface-waters of the Indian and Atlantic Oceans by the 

 use of a tow-net Later on, Owyn Jeffreys* asserted that 

 these were exclusively oceanic, and confined to the upper 

 stratum of the sea, in opposition to the opinions of his 

 associates, Wyville Thomson and Carpenter, that they were 

 abyssal. During the voyage of the Cliallenger Murray had 

 ample opportunities for proving the correctness of Jeflfreys' 

 statement, and showed lieyond doubt that these creatures 

 are indeed pelagic, and that only after death do their 



* Proc. Eoy. See. London, Nov. 121, p. 443. 



bodies subside to the bottom, where they form the basis of 

 a whitish deposit termed " Globigerina ooze " (Fig. 3), so 

 called from the preponderance therein of the tests of 

 Glohigerhin. 



We shall have occasion in future to point out that other 

 forms than Foramin\fera {f.g-, Radiolaria) live, die, and 

 are in like manner deposited. Fig. 4 shows two Radio- 

 larians drawn from living specimens. 



Fig. 4. — Eadiolaria ; a. Haliomma hecacanthum, one of the 

 rolycyslina, with radiating pseudopodia ; h. Acanthomefra lanceo^ 

 atai. ' (After J. JluUer, Abhandl. d. K. Akad., Berlin, 1S58). 



The shells of the fresh Gloliigerina: are pellucid, and of a. 

 firm consistency ; they are perforated by many pores, sur- 

 rounded externally by a kind of crest, so that the pore 

 commences at the bottom of an hexagonal pit ; at each 

 angle of this crest a delicate, long calcareous spine is given 

 ofl', and these radiate from the centres of the respective 

 chambers of the shell to which they belong. The whole 

 system of spines produces a marvellously beautiful effect, 

 and has been accurately figured and described by Wyville 

 Thomson ; * he has stated that pseudopodia have not beeri 

 discovered in these animals. 



After the tests sink to the bottom to produce the so- 

 called ooze, they become opaque, lose their spines, and 

 finally disintegrate. 



In Fig. 3, which represents a sample of Globigemia ooze 

 from the floor of the Atlantic, fragments of another or- 

 ganism may be observed. These are portions of the tests 

 of Orhulina universa, and may be readily distinguished 

 from those of Glohigerina by their pores, which are of two 

 sizes, one about four times as large as the other. Orhulina 

 is spherical in shape, and sometimes contains a series of 

 internal chambers, which resemble a small Glohigerina. 

 This led Max Schultze and others to suppose that it is but 

 a reproductive phase of Glohigerina. 



It has been shown by the Challenger results that Globi- 

 geriruK exist in vast numbers all over the surface of the 

 ocean, and are especially abundant in the warmer seas ; 

 accordingly, it would be but natural to suppose that the 

 deposit on the sea-bed should always contain their tests ; 

 but this is by no means the case, and was at first an enigma 

 to the naturalists of the I'halhnger, who came to a solution 

 of the difficulty through the following observations : — They 

 found that with increasing depth the nature of the deposit 

 varied — so much so that they were able to predict what it 

 would be at a given depth. At about 2.2-50 fathoms the 

 Globigerina ooze gradually changes into a " grey ooze," 

 which is characteristic of 2,400 fathoms. Deeper down 

 (2,700 fathoms), the deposit is known as "red clay." 

 From chemical experiments superadded to observed facts, 

 they were led to discover that the calcareous Globigerina 

 ooze is so acted upon by the solvent action of the sea water, 

 that it is gradually broken down into the grey ooze, and 



* Proc. Boy. Soe. London, 1874, No. 156, p. 35, Plate I. 



