124: THE AMERICAN MONTHLY [Jnlj, 



Practical study of blood.* — II. 



( Continued from page i lo.) 



The examination of blood corpuscles was continued, the blood of the bird 

 first claiming attention, the corpuscles being oval, nucleated discs, much 

 smaller than those of the frog or newt. Upon the same slide a drop of frog's 

 blood was placed for purposes of comparison, and as these corpuscles measure 

 in their greater length about i-ioooth of an inch, they were found exceeding 

 useful in determining the size of the other corpuscles. The presence of the 

 nuclei was demonstrated both by treatment with acetic acid and magenta. 

 The white corpuscles presented no features of special importance beyond 

 those already observed in the blood of the new^t. 



The examination of human blood was next vuidertaken, no little amuse- 

 ment being caused amongst the members taking part in it when directions 

 were given for each to prick his finger with a sharp needle for purposes of 

 supply. This, however, can be done without any appreciable pain by tightly 

 wrapping a piece of string round the end of the finger. Both the red and 

 white corpuscles were examined, the red ones being circular bi-concave discs, 

 a little less than one-third the diameter of the blood of the frog — that is, about 

 i-3300th of an inch — the thickness, when seen on edge, not being more than 

 one quarter of this. A marked difference between this blood and the bloods 

 previously examined was the tendency of the red corpuscles to run together 

 into rouleaux like rolls of coin. Between these a few white corpuscles were 

 visible, of irregular outline, and about i -3500th of an inch in diameter. 

 The absence of nuclei in the red corpuscles, and their presence in white cor- 

 puscles, was demonstrated by treating with magenta and with acetic acid. 

 The action of water in causing those corpuscles to swell, and of syrup in 

 causing them to shrink, was very mai-ked, the explanation of this being that 

 a lighter liquid difthses more rapidlv into a heavier one than a heavier into a 

 lighter. This action is known as osmosis. The action of a solution of common 

 salt caused the corpuscles to assume a peculiar crenated or spinose appearance, 

 a form often assumed by red corpuscles after leaving the body in certain condi- 

 tions of the blood, when they niav be mistaken for white ones. A drop of 

 human blood placed upon the slide for some little time and then examined 

 showed radiating structure of fibres which really forms from the blood plasma, 

 and is known as fibrin. This network held the corpuscles in its meshes, and 

 thus the cause of the formation of a blood clot was to some extent observed. 

 Another drop, to which a little common salt had been added, remained liquid, 

 and no such network of fibrin was formed, illustrating the use of certain salts 

 in preventing the coagulation or clotting of the blood, which, under normal 

 conditions, always takes place when it leaves a healthy blood-vessel. * * * 



Speaking of the contents of the red blood corpuscles, they were described 

 as consisting of 90 per cent, of the peculiar form of protoplasm know as 

 hcemoglobin difiused through the rest of the corpuscle, the stroma. It was 

 shown that this haemoglobin could be extracted from blood corpuscles and 

 even crystallized, a preparation of such crystals being projected upon the 

 screen bv the oxvhvdrogen microscope. It was also shown that these 

 hiemoglobin crystals could be dissolved in water and in blood serum, so that 

 it maybe inferred that the non-solution of the haemoglobin of the corpuscles 

 in the blood itself must be prevented by some peculiar property of the stroma 

 through which it is difiused. The rapidity with which a solution of haemo- 

 globin could absorb oxygen and lose it again was exhibited by projecting 

 upon the screen the spectrum of a hcemoglobin solution that had been shaken 

 up with air, when two dark absorption bands were visible in the green sep- 



* From report in English Mechanic of a meeting of the Manchester Microscopical Society. 



