BLOOD. 145 



animals that are born in an imperfectly developed con- 

 dition. 



The low temperature of persons with morbus coerulcus, in 

 whom the metamorphosis of the blood is always imperfect, and 

 the corresponding phenomena that are presented by aged, 

 debilitated, sick persons, and those in Avhom (according to 

 Edwards) a small quantity of blood circulates torpidly; as well as 

 the increased temperature in inflammatory diseases when the 

 blood cu'culates more rapidly than usual, and the metamoi'phosis 

 is more rapid, are other illustrations of the same principle. 



The phenomena obsened in hybernating animals are strongly 

 corroborative of the mutual dependence of the animal heat and 

 of metamorphosis, and also of the intimate connexion of the 

 former with the processes of respiration and circulation. 



The obsei*\'ations of Pallas, Spallanzani, Mangili, Saissy, 

 Czermack, and Berthold show that hybernation is prevented by 

 a temperature of from 50° to 80°, whilst it is induced in those 

 animals that are subject to it, even in summer, by means of arti- 

 ficial cold : other observers, however, maintain, that there is a 

 periodical deficiency of vital energy at the usual hybernating 

 season. During this peculiar state the respiration becomes 

 slow, and may even cease altogether ; the circulation is likewise 

 almost stopped, for Saissy foimd that the capillaries of the exter- 

 nal parts of the body were nearly empty, while the larger ves- 

 sels were only half filled, and the undulatorv^ motion of the blood 

 was observable only in the principal trunks of the thorax and 

 abdomen. He likewise found that the blood did not contain 

 the usual amount of fibrin and albumen at this period, and that 

 the bile had a peculiarly sweet taste. 



The production of heat is also dependent on the mass of 

 the blood- corpuscles, and on the rapidity of the cii'culation, — a 

 view that perfectly accords with the preceding statement, for 

 the corpuscles are {as we shall presently show) undergoing a 

 constant metamorphosis, which may be regarded as an e^ddence 

 of the \dtality of the blood, and which is intimately connected 

 with the respiratory process. 



When there is a paucity of corpuscles, the necessity for the 

 absorption of oxygen is diminished in a corresponding ratio, 

 the circulation becomes slower, and there is less heat developed 

 than in the normal state : on the other hand, blood with an 



10 



