Albert C. Eyclesliymer 309 



ScHWARZ, F., 87. — Die Morphologische und Chemische Zusammensetzung des 



Protoplasma, Breslau, 1887. 

 Weber, E., 74. — Note sur les noyaux des muscles striee chez la grenouille adu't. 



Arch, de physiol. norm, et path., Paris, 1874, T. VI, pp. 483-495. 

 Wilson, E. B., 00. — The Cell in Development and Inheritance. New York and 



London, 1896. 



LIST OF ABBREVIATIONS FOR ALL FIGURES. 



a., apex of cone of fibrillse. ky., karyosome. 



cm., cell membrane. l-, linin network. 



c. p., cutis plate. mes., mesenchymal nuclei. 



c. s., cytoplasmic strands. m. p., muscle plate. 



cy., cytoplasm. «-. nucleus. 



c. z., clear zone. pl-^ plasmosome. 



en., endomysium. s., septa. 



/=., fibrillse. y., yolk granules. 



f. c, fibrillar cone. 



EXPLANATION OF PLATE I. 

 All figures were outlined by the aid of the camera lucida. 



Fig. 1. — Represents an oblique longitudinal section through the third myo- 

 tome of a 6 mm. embryo, showing the relation of cutis plate and muscle plate, 

 the accelerated absorption of yolk granules in each end of the myotome and 

 the striations of the myoblast, x 100. 



Fig. 2. — Oblique longitudinal section of a .9 mm. embryo, showing same 

 points as above section, together with the clear zones at either end of the 

 myotome, x 100. 



Fig. 3. — Oblique longitudinal section of myotome of 12 mm. embryo, showing 

 increased extent of fibrillation, and invasion of mesenchymal cells to form 

 septa and endomysium. x 100. 



Fig. 4. — End of isolated myoblast from 8 mm. embryo, after osmic acid fixa- 

 tion, showing cone of striae or fibrillse. 



Fig. 5. — Prom freshly teased preparation, showing cytoplasmic strand con- 

 necting the ends of myoblasts in adjoining myotomes, x 700. 



Fig. 6. — Group of myoblasts from 15 mm. embryo, showing the septa, endo- 

 mysium, also the extent of fibrillation in the myoblasts, x 700. 



Fig. 7. — Group of contracted myoblasts from 26 mm,, embryo, showing the 

 growing septa, endomysium, peripheral position of nuclei and rows of yolk 

 granules, x 100. 



Fig. 8. — Isolated myoblast from 10 mm. embryo, after osmic acid fixation and 

 safranin, showing arrangement of fibrillge in the myoblast, x 700. 



Pig. 9. — Transverse section of a group of myoblasts, after Kolossow's osmic 

 acid method, showing the relation of the fibrillse to the cytoplasmic reticulum. 

 X 700. 



Pig. 10. — Transverse sections of myoblasts in .9 mm,, embryo, indicating 

 position of nuclei with reference to fibrillated area, x 500. 



Pig. 11. — Transverse section of myoblasts of 15 mm. embryo, showing vari- 

 ations in mode of extension of fibrillae and the position of the nuclei. X 500. 



