FORM AND SIZE OF THE BLOOD-CORPUSCLES. 



11 



scope. At first the corpuscles become globular, and so appear smaller, but after- 

 wards they burst like soap-bubbles. 



[Tannic Acid. A freshly prepared solution of tannic acid has a remarkable 

 effect on the coloured blood- corpuscles of man and animals causing a separa- 

 tion of the haemoglobin and the stroma. The usual effect is to produce one or 

 more granular buds of haemoglobin on the side of the corpuscles ; more rarely 

 the haemoglobin collects around the nucleus, if such be present (W. Roberts).] 



[Ammonium or Potassium SlllpllO-cyanide removes the haemoglobin, and 

 reveals a reticular structure mZra-nuclear plexus of fibrils (Stirling and Rannie).] 



The quantity of gases contained in the blood-corpuscles exercises 

 an important influence on their solubility. The corpuscles of venous 

 blood, which contains much C0 2 , are more easily dissolved than 

 those of arterial blood; while between both stands blood containing 

 CO (Landois, Litterski). When the gases are completely removed 

 from the blood, it becomes lake-coloured. 



6. Form and Size of the Blood-Corpuscles of 

 Different Animals. 



All mammals (with the exception of the camel, llama, alpaca, and 

 their allies), and the cyclostomata amongst fishes e.g., Petromyzon, 

 possess circular disc-shaped corpuscles. 



Elliptical corpuscles without a nucleus are found in the above-named 

 mammals, while all birds, reptiles, amphibians (Fig. 1, B, 1, 2), and fishes 

 (except cyclostomata) have nucleated elliptical bi-convex corpuscles. 



Amongst vertebrates, amphioxus has colourless blood invertebrates generally 

 have colourless blood, with colourless corpuscles ; but the earth-worm, and the 

 larva of the large gnats, &c., have red blood whose plasma contains haemoglobin, 

 while the blood-corpuscles themselves are colourless. 



[Elaborate measurements of the blood-corpuscles have been made in 



