Figure 13 is a cross section of one of the ocular muscles of a 23rd day frog-embryo, 

 and shows the developing muscle fibrils cut across transversely. The latter 

 develop in very definite bundles which show an intense reaction with the special 

 iron-alum haematoxylin stain that was employed, and are in striking contrast 

 to the comparatively achromatic myosyncytium in which they lie. X 1000. 



Sec. IV, 7C 



