THE BASIN OF THE ATLANTIC. 211 



chiefly made up of perfect little calcareous shells {Forami7iiferce), 

 and contain, also, a small number of silicious shells {BiatomacecB). 



" It is not probable that these animals lived at the depths where 

 these shells are found, but I rather thmk that they inhabit the wa- 

 ters near the surface ; and when they die, their shells settle to the 

 bottom. With reference to this point, I shall be very glad to ex- 

 amine bottles of water from various depths which were brought 

 home by the Dolphin, and any similar materials, either ' bottom,' 



or water from other localities. I shall study them carefully 



The results already obtained are of very great interest, and have 

 many important bearings on geology and zoology 



^' I hope you will induce as many as possible to collect sound- 

 ings with Brooke's lead, in all parts of the world, so that we can 

 map out the animalcula? as you have the whales. Get your wha- 

 lers also to collect mud from pancake ice, &c., in the Polar re- 

 gions : this is always full of interesting microscopic forms.'' 



449. These little mites of shells seem to form but a slender 

 clew indeed by which the chambers of the deep are to be thread- 

 ed, and mysteries of the ocean revealed ; yet the results are sug- 

 gestive ; in right hands and to right minds, they are guides to 

 both light and knowledge. 



The first noticeable thing the microscope gives of these speci- 

 mens is, that all of them are of the animal, not one of the mineral 

 kingdom. 



450. The ocean teems with liie, we know. Of the four ele- 

 ments of the old philosophers— fire, earth, air, and water— perhaps 

 the sea most of all abounds with living creatures. The space oc- 

 cupied on the surface of our planet by the different families of 

 animals and their remains is inversely as the size of the individ- 

 ual. The smaller the animal, the greater the space occupied by 

 his remains. Though not invariably the case, yet this rule, to 

 a certam extent, is true, and will, therefore, answer our present 

 purposes, which are simply those of illustration. Take the ele- 

 phant and his remains, or a microscopic animal and his, and com- 

 pare them. The contrast, as to space occupied, is as striking as 

 that of the coral reef or island with the dimensions of the whale. 

 The grave-yard that would hold the corallines is larger than the 

 grave-yard that would hold the elephants. 



451. We notice another practical bearing in this group ofphys- 



