ITS PHYSICAL, CHEMICAL, AND STRUCTURAL CHARACTERS. 239 



174. The form of the Red Corpuscles is not uufrequently seen to change 

 during their circulation ; but this is generally in consequence of pressure, 



FIG. 104. 



Various forms assumed by blood-corpuscles after withdrawal from the body. The first represents an 

 oval corpuscle of the frog breaking up into segments. The corpuscle marked a exhibits the formation 

 of a crystal within a red corpuscle (Owsiannikow). 6, e, d, forms represented by Bottcher. The re- 

 mainder are from Mr. Gulliver's drawing. 



from the effects of which, however, they quickly recover themselves. In the 

 capillary vessels they sometimes become suddenly elongated, twisted, or bent, 

 through a narrowing of the channel ; and this change may take place to 

 such a degree as to enable the disk to pass through an aperture which ap- 

 pears very minute in proportion to its diameter. The size of the blood-disks 

 is liable to considerable variation, even in the same individual ; some being 

 met with as much as one-third larger, whilst others are one-third smaller, 

 than the average. The diameter of the corpuscles bears no constant rela- 

 tion to the size of the animal, even within the limits of the same Class; 

 thus, although those of the Elephant (2, Fig. 103) are the largest among 

 Mammalia (as far as is hitherto known), those of the Mouse tribe are far 

 from being the smallest, being, in fact, more than three times the diameter 

 of those of the Musk Deer (3, Fig. 103). There is, however, as Mr. Gulliver 

 has remarked, a more uniform relation between the size of the animal and 

 that of its blood-disks, when the comparison is made within the limits of the 

 same Order. In Man, their diameter commonly varies from about -5-^0 o^ 

 to ^Too^h of an inch, with still wider extremes ; the average diameter is 

 about -g-^ooth > an( ^ their average thickness, according to the same excellent 

 observer, is about y^yoth of an inch. According to the estimates of Vie- 

 rordt, which have been corroborated by Mautegazza, a cubic centimetre of 

 human blood contains about 5,000,000 red corpuscles (in the male, 4,500,- 

 000 in the female), and about 14,000 colorless ones. M. Malassez 1 finds that 

 the number of corpuscles varies in different parts of the circulation, the 

 largest number being contained in the smaller arteries and capillaries 

 (4,300,000), and a smaller proportion in the larger arteries and veins 

 (4,000,000, vein of arm). The richness of the blood, however, is not de- 

 pendent alone on the number of the corpuscles, but upon their volume and 

 the quantity of haemoglobin they contain. The color of the Red Corpuscles 



1 De la Numeration des Globules Eouges du Sang. Pamphlet, Paris, 1873 ; also 

 Abstract by Dr. Furrier in Medical Record, Jan. 8th, 1873. In this method of esti- 

 mation the blood is drawn into a capillary glass-tube of known diameter, diluted with 

 a definite quantity of serum, and the corpuscles counted. Among mammals the 

 number varies from about 3,500,000 (Rabbit) to 18,000,000 (Goat) in the cubic cen- 

 timetre. Camels possess about 10,000,000; Birds (Cock), 2,000,000-3,300,000; Osse- 

 ous Fishes, 700,000-2,000,000; Cartilaginous Fishes, 140,000-230,000. 



