FORM AND COLOUR OF THE BLOOD-CELLS. 171 



the formation of such forms; thus a drop of blood, when it has 

 remained on the stage, and the water has in part evaporated, 

 exhibits these jagged corpuscles ; we usually observe the same 

 appearance in the very saline sputa of catarrh al and phthisical 

 patients, if haemoptysis be present. 



In the portal blood of an animal, immediately after it has been 

 killed, we not unfrequently find (according to Schmidt) distorted 

 and jagged bodies of this nature, but they do not occur in the 

 blood of the hepatic veins : this difference may possibly depend 

 on the difference in the quantity of salt contained in the serum of 

 the two kinds of blood ; for the serum of the portal blood is richer 

 in chloride of sodium than that of other venous blood, even when 

 the former is of comparatively low density. 



With regard to the different substances which simultaneously 

 act on the form of the cells and the colour of the blood, we shall 

 here only briefly give the results which we have ourselves obtained, 

 since the statements of different authors present great discrepancies 

 in many points, as might easily be expected. 



Amongst the most striking of these phenomena is the expansion 

 of the corpuscles and the simultaneous darkening of the blood on 

 the addition of various quantities of water. The swelling of the 

 lenticular blood- corpuscles is proportional to the quantity of water 

 which is added ; they swell, however, in one diameter more than 

 in the other; their concavity on each side disappears, and is 

 replaced by a convexity, so that finally they become converted 

 into spherical vesicles. These often appear to the eye smaller 

 than the pre-existing discs, since it is little more than their trans- 

 verse diameter that is enlarged, while their long diameter is 

 diminished, if at least only small quantities of water are added. 

 The corpuscles are then very similar to fat globules, except that 

 they are less glistening and less distinct in outline, as if they had 

 been faintly breathed upon. When the corpuscles have absorbed 

 a large quantity of water, their coefficient of refraction approximates 

 so closely to that of the intercellular fluid, that they can no longer 

 be perceived through the microscope. By the addition of salts to 

 this fluid the blood-corpuscles may again become apparent in their 

 normal form; for the most part, however, they then appear 

 distorted, jagged, or star-shaped. If the blood has been treated 

 with a very large quantity of water, the cell-wall completely 

 bursts, and of course no addition of salts can then restore the 

 integrity of the corpuscles ; they then form transparent, granular 

 conglomerations, which may be rendered visible by being treated 



