BiORLOW. — Development of Lepas. 



PLATE 5. 



Figures from transparent preparations of entire eggs. Vegetative pole at the 

 left in figures which represent lateral views. 



Fig. 39. Kight-cell stage from animal pole. The seven " protoplasmic " cells are 

 in tiie fourth cleavage; the nucleus of yolk-cell (d^'^) is preparing for 

 division. 



Fig. 40. Same egg in lateral view. Yolk at vegetative pole of cell c/*i. 



Fig. 41. Fifteen "protoplasmic" cells; the yolk-cell (</^"S mes-entoblast) divid- 

 ing. Lateral view. 



Fig. 42. Sixteen-cell stage from animal pole. Nuclei of all cells are in " resting " 

 phase. Primary mcsoblast (#-) separated from entoblast (ci°'^). 



Fig. 43. Same egg viewed from vegetative pole. Oil spherules near lower surface 

 of the yolk-cell. 



Fig. 44. Sixteen-cell stage from animal pole. All cells, except yolk-cell (entoblast 

 d^i) and the primary raesoblast cell (#'2), are undergoing the fifth 

 cleavage. 



Fig. 45. Same egg in lateral view. 



Fig. 4G. Same stage from vegetative pole. The three mcs-ectoblasts (compare 

 Fig. 43, w>'-, b^'^, c^ 2j contiguous to yoik-cell. 



Note. — Cell ct^- is represented as divided, and its derivatives should have been 

 labelled aO-3, aS*. 



