

Fig. 27 From an embryo of the early-swimming stage, at the level between 

 the fifth and sixth myotomes. Same treatment, plane and thickness as in case of 

 figure 25. X 470. 



Fig. 27a From an embryo of the early-swimming stage; fixation in Zenker's 

 solution; stained in iron hematoxylin; plane of section oblique vertical-horizontal; 



thickness, 7 yu. X 470. 



217 



