108 THE PHYSIOLOGY OF EARTHWORMS 



haemoglobin Manwell (1959) suggests that the triphasic denatura- 

 tion represents a three-step denaturation of one haemoglobin type 

 that has three monomolecular forms. This idea would support the 

 sedimentation and absorption spectra data, although if more than 

 one haemoglobin is present it is not inconceivable that the molecu- 

 lar w^eights and hence sedimentation constants will be the same. 

 A little more information is given by electrophoretic studies on 

 the blood of L. terrestris. A spot of blood, separated by electro- 

 phoresis on a cellulose acetate membrane, gives rise to a number of 

 fractions. At least three are observed, and one appears only on 

 staining with nigrosin. The other two bands are both visible to the 

 naked eye as yellow-orange in colour and are obviously the haemo- 

 globin of the blood. They stain with leucomalachite green, 

 commonly used for the demonstration of haemoglobin. Similar 

 results have been obtained for A. longa, and E. foetida (Laverack, 

 1960, unpubhshed). The evidence supports the theory that two 

 haemoglobins are actually present at the same time, and it is felt 

 that more information could be gained from experiments using 

 moving boundary electrophoresis. 



Cellular Respiration 



Ultimately the process of respiration involves a consideration of 

 the energy cycles of the cells that make up the body of the animal. 

 The oxidation-reduction processes of the cells are the final links in 

 the chain that started with the exchange of gases across the body 

 wall. These oxidation processes of the cells of earthworms in- 

 volve a heavy metal prosthetic group oxidase, presumably a 

 cytochrome-cytochrome oxidase system. This series of enzymes is 

 blocked by KCN, and Petrucci (1955) finds that the respiratory 

 rate oi E. foetida in the presence of KCN is only 9% of the normal 

 level. Peloscolex velutiiius has a KCN resistant respiratory fraction 

 amounting to 16%. Thus the heavy metal oxidase accounts for 

 84% of cellular respiration in P. velutiniis and 91% in E. foetida. 

 The concentration of cyanides required to block 50% of the 

 oxygen uptake is 7-3 x 10-^ M KCN for E. foetida and ll-8x 10-5 

 M KCN in the case of P. veliitinus. 



Carbon monoxide, which combines with haemoglobin to the 

 exclusion of oxygen, depresses the respiratory exchange of P. 

 velutinus and E. foetida. It reduces respiration by 50% when 



