102 CIRCULATING FLUIDS: 



1045. In very young infants the blood is thin, and of low- 

 specific gravity ; according to Denis the blood of the umbiHcal 

 arteries has a specific gravity of 1075. The specific gravity of 

 the blood of numerous animals has been determined by Dr. 

 J. Dav}'i and by Nasse.] 



I found that the blood, as it issues from the aorta, has 

 a tem])erature of 103° in the ox, and 99° '5 in the pig. 

 Thackray places the temperature of the blood of the horse 

 at 96°-8, of the ox at 99^-5, of the sheep at 101 ''•3, and 

 of the duck at 105*^'8. The temperature is always higher in 

 birds than in the mammalia. The observations of J. Davy, 

 Becquerel, Breschet, Mayer, and Saissy, tend to show that 

 the temperature of arterial is about 1°*8 higher than that of 

 venous blood. 



Microscopic analysis of the blood. 



If the blood be examined with the microscope (either in a 

 transparent living part, or immediately after its removal from 

 the body), it will be seen to consist of a great number of 

 yellow corpuscles swimming in a colourless fluid. In the 

 higher animals the form of these corpuscles is either circular 

 or elliptic, and invariably flattened. 



Under a magnifying power of 300 diameters, they assume 

 the appearance of fig. 1 a in the blood of man and the mam- 

 malia, of fig. 1 6 in the blood of birds, and of fig. 1 c in 

 the blood of fishes and amphibia. Mviller- found the greatest 

 degree of flattening in reptiles, amphibia, and fishes. He 

 found that in frogs the thickness does not measure more than 

 one eighth to one tenth of the long diameter, and that in man 

 it measures about one fourth or one fifth of the transverse 

 diameter. 



In addition to the blood-corpuscles, lymph-, chyle-, and 

 sometimes oil-globules are present. The first two are round, 

 of a finely granular appearance, and about the size of the 

 blood-corpuscles, from which they may be distinguished by 

 their want of colour, their more perfect sphericity, and their 

 granular appearance. 



' Anatomical and Physiological Researches, j). 2-J. 



^ Ilandbuch dcr Physiologic dcs Mcnschoii, vol. 1, p. 105. 



