632 SANGUIFICATION. 



mammalia, greater in the latter than in reptiles,* 

 and greater in reptiles than in fishes. In ac- 

 cordance with this fact, we learn from the ac- 

 curate researches of Dr. John Davy, that the 

 specific gravity of the blood in these four classes, 

 varies in the following proportions : 



Arterial. Venous. 



Turkey 1061 .. 



Lamb 1047 .. 1050 



Dog 1048 .. 1053 



Frog 1040 



Codfish 1034 



But there is reason to believe from the experi- 

 ments of Denis, Le Canu, Marshall, and others, 

 that the ratio of fibrin and red particles, is higher 

 in the blood of birds and mammalia, than was 



* Prevost and Dumas found the blood of a tortoise, which had 

 been five months in a state of lethargy, to contain 15*06 per 

 cent, of solid matter, owing, as they rightly supposed, to the 

 loss of a large proportion of water by exhalation or transudation. 

 And it will be seen hereafter, that owing to the same cause, 

 (transudation of serum or water,) the proportion of red particles 

 is greater in many cases of malignant cholera, than during the 

 most vigorous state of health. (Examin. du Sang. Ann. de 

 Chim. et de Phys. vol. xxiii.) But Mr. Marshall was so kind 

 as to perform some analyses at my request, which show that 

 the blood of the tortoise, while in a state of activity, does not 

 afford above 8 per cent, of solid particles, and that of the sala- 

 mander about 7 '54. It may therefore be presumed, that the 

 blood of all young birds hatched without feathers, and of mam- 

 malia born with the eyes closed, whose power of maintaining 

 their temperature by respiration, is for some days very imperfect, 

 is less highly organized than at later periods, corresponding with 

 the feebleness of all their vital functions. * 



