SyVNGUlFICATION. 203 



their exact form and nature, and from the impor- 

 tance which is supposed to attach to them, as being 

 an essential component part of the blood, and as 

 a material element in the formation of the solid 

 structures of the body. They generally appear to 

 contain a solid central nucleus, enveloped by a 

 vesicle to which the colouring matter of the blood, 

 termed hematine, or hematosine, is attached. Their 

 size and form vary much in different animals, and 

 sometimes even in the same animal at different 

 periods of its life ; and appear to have no relation 

 to the size or habits of the animal. In man, their 

 diameter is, on an average, about the 5000th part 

 of an inch ; and they are nearly of this magnitude 

 in the dog, in the hare, and in the mouse. In the 

 horse, ox, and sheep, their diameter measures one 

 0100th ; and in the stag and goat, only the 87G0th 

 part of an inch. In birds, reptiles and fishes, their 

 figure is generally elliptical, and their size is greater 

 than in the mammalia. They are largest of all 

 in the Batrachian reptiles ; in the water newt, (Sala- 

 mandra cristata), their diameter is five times greater 

 than in man ; and in the Proteus miguiuus, they 

 are even eight times larger ; their diameter being 

 as much as the 640th of an inch. Remarkable 

 varieties in the form of these corpuscles occur in 

 the blood of several species of Deer,* some having 

 the figure of a crescent ; others of the letter S ; 

 others being shaped like a comma, or like the head 



* Such as the Cervus Reevesii, or Muntjac ; the Cervus porcinus, 

 or Porcine Deer, and the Cervus Mexicanus, orMexican Deer. The 

 observations relating to the forms of the corpuscles in these animals 

 were made by Mr. George Gulhver. See Proceedings of the Royal 

 Society, Feb. 6, 1840, p. 199. 



