ASPLANCHNA EBBESBORNII (ROTIFER) 



403 



inner cell content (the invaginated stomodaeum and the deriv- 

 atives of the mesentoblast) (text figs, g, h, and q). Other rows 

 of proliferated cells at either end are connected with the ectoderm 

 (text fig. k). Many of these cell processes have several attach- 

 ments (text fig. h), but in their further development some of 

 these points of fusion are lost and the developing muscle remains 

 attached to the later formations, which they are destined to 

 control. The muscle fibers, in their early formation, are com- 



Figs. g and h Early muscle cells connecting ectoderm with inner structures. 



Figs, i and j Early and definitive stages of muscle-fiber development. 



Figs, k and 1 Shows method of attachment in the early and late development 

 of muscle fibers. 



Fig. m A completely formed muscle, showing attachment to brain and 

 ectoderm. 



Fig. n A network of muscle fibers extending across body cavity. 



ABBREVIATIONS 



b.c, body cavity 

 6?'., brain 

 cp., corpuscle 

 ect., ectoderm 



m.c, muscle cell 

 m.f., muscle fiber 

 tr., trochus 

 w.ph., wall of pharynx 



