OF THE ANIMAL FRAME. 115 



enamel of teeth possessing 1 the largest quantity, and consisting- almost exclu- 

 sively of phosphate of lime, with a small proportion of animal matter. 



The gelatin and albumen are unquestionably generated in the animal sys- 

 tem itself from the different substances it receives under the form of food ; 

 and it is curious to observe the facility and rapidity with which some animals 

 are capable of producing them. The gastrobranchus ccecws, or hag-fish, a 

 small lamprey-like animal of not more than eight inches long, will convert a 

 large vessel of water in a short period of time into size or mucilage, of such 

 a thickness that it may be drawn out in threads. The form and habits of 

 this little animal are singular: Linnaeus re-garded it as a worm ; but Bloch has 

 removed it, and with apparent propriety, into the class of fishes.. It is a cun- 

 ning attendant upon the hooks of the fisherman ; and as soon as it perceives 

 a larger fish to be taken, and by its captivity rendered incapable of resistance, 

 it darts into its mouth, preys voraciously, like the fabled vultures of Prome- 

 theus, on its inside, and works its way out through the fish's skin. 



But though gelatin and albumen are unquestionably animal productions, 

 the one a secretion from the blood, and the other a constituent principle of it, 

 there is a doubt whether lime ought ever to be regarded in the same charac- 

 ter. A very large portion is perpetually introduced into the stomach from 

 Avithout. In our lecture on the analogy between the structure of plants and 

 of animals,* I had occasion to observe, that it forms an ingredient in common 

 salt ; not, indeed, necessarily so, but from the difficulty of separating the 

 other ingredients from their combination with it : yet it enters not more freely 

 into common salt than into almost every other article, whether animal, vege- 

 table, or mineral of which our diet is usually composed. And upon this com- 

 mon fact it is more generally conceived, at present, to be a substance com- 

 municated to the animal frame, than generated by it. 



This opinion, however, is by no means established; and there are many 

 circumstances that may lead us to a contrary conclusion. Though almost 

 every kind of food contains some portion of lime, it by no means contains an 

 equal portion ; and yet we find that a healthy young animal, whatever be the 

 sort of food on which it is fed, will still provide lime enough from some quar- 

 ter or other to satisfy the demand of its growing bones, and to maintain them 

 in a due degree of solidity and hardness. 



Again, the soil of some countries, as the mountains of Spain, for example, 

 consists almost entirely of gypsum or some other species of limestone ; while 

 in other countries these are substances very rarely to be met with. It 

 is a curious fact, that in that vast part of the globe which has been latest dis- 

 covered, and to which modern geographers have given the name of Australia, 

 comprising New-Holland and the islands with which its shores are studded, 

 not a single bed or stratum .of limestone has hitherto been detected, and the 

 builders are obliged to make use of burnt shells for their mortar, for which 

 I have lately advised them to substitute burnt coral.f Now, it would be 

 natural to suppose that the animals and vegetables of such a country would 

 partake of the deficiency of its soil, and that the shells and bones which it 

 produces would be less compact in their texture than those of other countries ; 

 yet this supposition is not verified by fact : nature is still adequate to her own 

 work ; the bones of animals are as indurated and perfect in these regions as 

 in any parts of the old world ; while the shells are not only as perfect, but far 

 more numerous ; and the frequent reefs of coral, altogether an animal pro- 

 duction, that shoot forth from the shores in bold and massy projections, prove 

 clearly that a coral rock, largely as it consists of lime, forms the basis of 

 almost every island. 



The prodigious quantity of lime, moreover, that is secreted by some ani- 

 mals at stated periods, beyond what they secrete at other times, seems to 

 indicate a power of generating this earth in their own bodies. The stag, elk, 

 and several other species of the deer-tribe, cast their antlers annually, and 



* Series i. Lect. viii. 



t It is understood that some beds of chalk have since been discovered on the farther side of the Blue 

 Mountains, but none is still to be traced on the hither side in any of the settlements of the colonv. 



H2 



