BIOCHEMICAL ARCHITECTURE 



that the organization of earthworm muscle is that of a sarcoplasmic 

 reticulum. The arrangement is of smooth muscle fibres with 

 heHcally arranged myofibrils. 



^ (b) 



(a) 



Fibril ' 



rl 



--10° 



(c) 



Fig. la. Diagram of a transverse section through a longitudinal 

 muscle fibre in the body wall of an earthworm (a). The fibre is 

 ribbon-shaped (b). The angles between the fibres are indicated 

 in the stretched and contracted conditions (c). 



The proteins of this organized tissue have been separated by 

 electrophoretic means. Five fractions in all have been noted, one 



B 



