160 THE BLOOD. 



temporary restoration of energy took place; but that, if it differed in their 

 shape, convulsions and death were the result. They also find a larger propor- 

 tion of fibrin and red globules in warm than in cold blooded animals, and a 

 larger in the former according to the height of the temperature (of 10,000 

 parts by weight; in pigeons, 1557; man, 1292; frogs, 690); a smaller, also, 

 accordingly as animals are bled ; it thus appearing that bleeding promotes the 

 absorption of watery fluid. (Annales de Chimie, t. xviii. xxiii. 1821 and 1823.) 

 The colour of the particles differs in different animals: hence red and white 

 blooded animals. 



Hewson (1. c. part iii. p. 39. ) saw the red particles of the blood of the fetal 

 chicken and viper larger than those of the adult animal : and Prevost and 

 Dumas have observed the red particles of the foetal goat to be as large again as 

 those of the adult ; and those of the chicken to be circular, till about the sixth 

 day, when some elliptic ones are first seen ; and on the ninth, from their progres- 

 sive multiplication, none but elliptic ones can be detected. (Annales des Sciences 

 NatureOes, 1824, 1825.) 



In the frog the particles are ^ and in the salamander even ,J 5 , of a millimetre, 

 the largest known. 



The blood of invertebral animals is colourless, but has not been analysed. 



The temperature of the blood, in general, varies with that of the animal. 



The sap of vegetables is different, accordingly as it is examined when ascending 

 from the roots, or descending again. The ascending sap is chiefly a watery solu- 

 tion of alcaline, earthy, and even metallic matters, and the proportion of water is 

 very large, on account of the little solubility of many of these ; the descending, or 

 returning sap, is the same concentrated by exhalation from the leaves, and loaded 

 with carbon, obtained in them from the atmosphere. 



The former may be compared to chyle, the latter to blood ; and this is more 

 and more elaborated and converted into various organic substances, so as to 

 be saccharine, fecular, glutinous or milky, oily, resinous, gum-resinous, and 

 oleo-glutinous. 



All vegetable principles are divided by Dr. Prout (Sridgewater Treatise, 

 p. 454. ) into three great classes those in which oxygen and hydrogen are com- 

 bined in the proportions which form water the saccharine ; those in which hy- 

 drogen, or rather carbon and hydrogen, predominate the oily; and those in which 

 oxygen predominates the acid. Some contain azote also, like animal principles, 

 from which, indeed, it is never absent ; and some, weak alcaline powers, as 

 quinine, morphine, &c. 



About forty years after the discovery of the circulation of the blood, trans- 

 fusion was practised upon brutes, and at length upon the human subject, though 

 some contend that the operation was known tb the ancients. Experiments were 

 made upon the effects of injecting medicated liquids into the blood, first by 

 Wahrendorf, in Germany. It was ascertained that they exert their specific 

 powers exactly as when swallowed, cathartics, v. c. purging, and emetics 

 emptying the stomach. Among other liquids, Dr. Christopher Wren proposed 

 that blood should be injected, and Dr. Lower first put this into practice. It 



