ITS COMPOSITION IN ANIMALS. 21 



matter than those of lean ones, and hence the bones of hybernat- 

 ing animals contain considerably more fat before than after their 

 winter-sleep. According to Stark, human bones are richer in 

 water than those of any other mammal. 



Von Bibra almost invariably found more bone-earth in the 

 bones of birds than in those of mammals. The rasores were the 

 richest in mineral substances (the mean being 75'8-g-; in Columba 

 Furtur the earthy matter rose to 84'3g-). The bones of carnivorous 

 birds are generally only slightly richer in earthy salts than those of 

 mammals. The ratio of the carbonate of lime to the phosphate 

 is generally greater in the bones of birds than in those of mammals. 

 There is, on an average, rather more fat in the bones of birds than 

 of mammals, and the granivorous, and especially the aquatic birds, 

 in this respect exceed those living on flesh. According to Stark, 

 the bones of birds contain more water than those of mammals. 

 Moreover, the bones of granivorous birds contain rather more 

 silica than other bones. 



Stark has also instituted comparisons between the organic and 

 inorganic substances in the bones of mammals and birds, but his 

 results are not in accordance with those of von Bibra. In all 

 probability, the osseous substance had not been perfectly dried in 

 most of Stark's comparative analyses. 



Our knowledge of the composition of the bones of the 

 amphibia is almost entirely due to the labours of von Bibra. 

 These bones contain an average less inorganic matter than those of 

 mammals and birds (those of the Salamandrida, for instance, only 

 55f, and those of the frog 63$) ; moreover, the ratio of the 

 carbonate of lime to the earthy constituents generally, is less in 

 the bones of the amphibia than in those of the preceding classes. 

 As has been already stated in vol. I, p. 444, von Bibra found a 

 considerable quantity of sulphate of soda* in these bones. 



The bones of fishes are poorer in mineral constituents than 

 those of any of the preceding classes (the earthy matters varying 

 from 21 to 57^). Although, with regard to the earthy salts, the 

 carbonate of lime appears to a certain extent to rise and fall with 

 the phosphate, no definite proportion can be detected as existing 

 between them. As in the case of the amphibia, von Bibra found 

 that these bones contained more sulphates and fat than those of 



* [The Editor regrets to find that a rather important erratum escaped his 

 notice in correcting the page referred to in the text. In line 8 from the bottom 

 of page 444, read " sulphate of soda" in place of " soda."] 



