THE BLOOD. 



165 



Fig. 98. 



Whipped blood also contains certain morphological elements 

 called fibrinous flakes. They do not, however, consist of fibrine, 

 but are more allied, chemically, to horny substances ; consisting of 

 epithelial cells, partly from the inner coat of the vessels, and partly 

 of fragments from the cuticle of the observer, as Briich suggests, 

 which have fallen into the blood. The fragments of destroyed cell- 

 membranes have also been mistaken for them. 



The cell-membrane of the blood-corpuscles being powerfully en- 

 dosmotic, the latter undergo changes of form from currents between 

 their contents and the intercellular fluid, and hence, also, changes 

 in specific gravity. The latter, of course, increases when water is 

 abstracted from them, and vice versa. Evaporation, or the addition 

 to the blood of small quantities of neutral alkaline salts, sugar, or 

 gum, may remove a part of the water; when they may present the 

 shrivelled appearance represented by 

 Fig. 98. Eepeated bleedings also in- 

 crease the specific gravity of the blood- 

 corpuscles. (Lehmann.) 



On the other hand, an increase of 

 water in the corpuscles diminishes their 

 specific gravity, and may distend them 

 till they become almost spherical, or 

 even burst. Hence their lower specific 

 gravity in anemia. They are also 

 lighter when they contain an excess of 

 fatty granules. 



These changes in the weight and the form of the blood-cells affect 

 both their tendency to sink in the plasma (and thus modify the ap- 

 pearance of the clot), and also modify the color of the blood. 



1. The "tendency to sink" is increased by an increased specific 

 gravity of the corpuscles ; and, apparently, also by an excess of car- 

 bonic acid in the corpuscles, and a diminished 

 quantity of albumen in the serum. At least, 

 the blood in inflammations manifests the pecu- 

 liarities of composition just mentioned ; and in 

 this state, also, the corpuscles sink more rapidly 

 than those of healthy blood. The effect of this 

 peculiarity on the color of the clot has been 

 alluded to (p. 93). The aggregation of the Biood-corpuscies i 

 corpuscles into nummular rolls (Fig. 99) seems mular rolls ' Surfaces en ~ 



J* \ o / tirely adherent at a, and 



to be a consequence, rather than a cause, of this partially at &. 



Blood-corpuscles shrivelled by chemical 

 agents. 



Fig. 99. 



