8 



THE PHYSIOLOGY OF EARTHWORMS 



being haemoglobin presumably from blood contained within the 

 muscle layers. Of the other fractions two are albumen and two are 

 myosin, termed a and ^ and which are claimed to be equivalent to 

 those of vertebrates (Godeaux, 1954) (Fig. 2). 



Fibril 



(b) c 



0-5// 



(c) 



(d) 



"Filoments- 



FiG. lb. Diagrams to show the arrangement of stripes and bridges 

 in a muscle fibre, (a) A fibre cut in transverse section, (b) An enlarged 

 view of the area marked in (a). Black regions marked c-c, d-d are 

 those further enlarged in Figs, (c) and (d) (from Hanson, 1957). 



The similarity of myosin obtained by fractionation from an 

 earthworm, Pheretima communis sima, with that of striated insect 

 and vertebrate muscle has been pointed out by Maruyama and 

 Kominz (1959). The major differences lie in the viscosity and flow 



I 



