182 BLOOD. 



instance, as putrefaction, must act on the form of the corpuscles 

 and give rise to chemical changes. Hence we need not wonder at 

 meeting with blood-corpuscles of the most varied forms in the 

 blood of dead bodies or in old exudations. It is, however, only 

 rarely that we can draw any conclusions regarding the pre-existing 

 disease from these forms ; for they are not the direct result of a 

 morbid process, but merely the consequence of the chemical or 

 physical changes to which the intercellular fluid is exposed. 

 We must not, therefore, expect any great advantage for medical 

 diagnosis from the microscopic examination of such blood ; on the 

 one hand, because such changed forms of the corpuscles never 

 occur in fresh blood (although they were formerly supposed to 

 have been found in the blood in cases of typhus) ; and on the 

 other, because blood obtained from the dead body always rapidly 

 undergoes essential changes from external influences. 



Having thus considered the physical characters of the blood- 

 corpuscles, we now proceed to the investigation of their chemical 

 constituents. This is a subject on which there is still much that is 

 obscure. The microscopic examination of the blood has certainly 

 taught us that its pigment is limited to only the coloured cells ; 

 Berzelius has further shown that in these cells there is contained 

 an albuminous fluid, differing, however, from albumen, which he 

 named globulin, and expressed his belief that the phosphorised fat 

 was in all probability only contained in the blood-cells. The 

 same chemist likewise indicated the way by which the blood- 

 corpuscles might be separated from the intercellular fluid, or by 

 which, at all events, they might be obtained free from the consti- 

 tuents of the serum, although with the loss of several of their own 

 essential constituents. Dumas and Figuier were the first to apply 

 this method to actual practice ; and the former, by this means, 

 was enabled to submit to an elementary analysis the dried frag- 

 ments of blood-corpuscles ; but, from the very nature of the case, 

 all these investigations could lead to very few conclusions regard- 

 ing the true and essential constituents of these coloured cells; 

 for we were investigating either the blood-cells mixed with inter- 

 cellular fluid, or merely the cells more or less completely freed 

 from all soluble substances (penetrating the cell-walls). We are 

 indebted to the ingenious and careful investigations of C. Schmidt 

 for a .more definite knowledge regarding the composition of the 

 contents of the blood^ corpuscles, and the nature of the individual 

 substances occurring in them. We shall see that in this discovery 

 of Schmidt's lies the nucleus of all our knowledge and theories 



