THE BASIN OF THE ATLANTIC. 211 



chiefly made up of perfect little calcareous shelh {ForaminiferceX 

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



" 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 hav€ 

 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 Avhales. 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 life, 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, certain extent, is true, and will, therefore, answer our present 

 purposes, which are simply those of illustreition. 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 of phys- 



