THE MUSCLES OF THE FLY. 187 



developmental history of the two structures is also remarkably 

 similar. Both are developed from cells with numerous nuclei, 

 some of which form the tubular wall, whilst others become con- 

 verted into muscle rods in the muscle, and blood corpuscles in the 

 capillary. The development of the fibrillee of the muscle from 

 nuclei is no longer doubtful in insects at least, and the fibrillee may 

 be regarded as united muscle rods. 



I shall reserve for a future paper some observations on the 

 muscle fibres of the dorsal vessel and alimentary canal in insects. 



