FIXED SALINE CONSTITUENTS. 39 



From this table we learn that the proportion of fixed saline constituents in the 

 blood, is remarkably uniform throughout the whole animal kingdom. This fact 

 demonstrates their importance. 



In the invertebrata they exist in larger amount relatively to that of the organic 

 constituents of the blood than in vertebrate animals. Thus, in the blood of the 

 Esculent Snail (Helix pomatia) there were, according to Harless and Bibra, 6.12 

 parts of mineral, and only 8.39 parts of organic substances. In the blood of Asci- 

 dians and Cephalopoda, Bibra found 4.7 parts of organic, and 2.63 parts of mineral 

 substances. When we consider the constitution of the shells of these animals, it is 

 not wonderful that the blood should contain so large a proportion of mineral sub- 

 stances. Schmidt found the albumen of the blood of the Pond Mussel (Anodonta 

 cygnea) combined with lime. This fact shows that these mineral bodies are chemi- 

 cally combined with the organic constituents of their bodies. 



Amongst vertebrate animals, we find the largest amount of mineral constituents 

 in the blood of Fishes and Reptiles inhabiting the salt water. The only exception 

 to this rule, was found in the blood of the Loggerhead Turtle (Chelonia caretta), 

 which had been kept, for forty-eight hours previous to this analysis, in a tub of 

 fresh water. It is possible that an interchange may have taken place between the 

 exterior water and the salts held in solution in the blood. The blood of the Hog- 

 nose Viper (Heterodon platyrhinoe) yielded a larger amount of ash than that of any 

 other animal. This is accounted for by the fact that the reptile had been starved 

 for a length of time, and the blood was in a concentrated condition. The Alligator 

 is classed amongst the salt-water Reptiles, because it had resided in a small salt- 

 water stream, in a salt marsh. This reptile inhabits, most generally, the brackish 

 and fresh-water rivers, lakes, swamps, and rice-fields. 



That the fixed saline constituents are absolutely necessary, not only for the forma- 

 tion of the different structures, but also for the maintenance of life itself, was 

 conclusively demonstrated by a series of experiments performed in France. It was 

 found that when animals were fed upon grain, from which only one element (phos- 

 phate of lime) was abstracted, they rapidly lost their forces, and died in the course 

 of a few weeks. 



Having completed the study of the blood in its normal condition, we are now 

 prepared to investigate the effects of starvation and thirst. 



