Plate XIII 



PLATE XIII 



proemlDryo of Ritppia rostellata, showing 

 nd two smaller embrj^o-cells. After Mur- 



Fig-ure 98.— Three-celled proemlaryo of Ritppia rostellata, showing 



basal suspensor-cell and ^■— "— — ' "" ''^'— '"'■- 



beck. X 446. 



Figure 99. — Nine-celled embryo of Rtippia rostellata, showing basal 

 suspensor-cell and eight small embryo-cells. After Wille. X 340. 



Figure 100. — Thirteen-celled embryo, showing division into three 

 transverse segments of four cells each, and a large suspensor- 

 cell \\'ith nucleus and cytoplasm in the characteristic j^osition. 

 X 800. 



Figure 101.— Longitudinal section through older embryo, the lieavy 

 lines marking the outlines of the cells shown in figure 100. 

 X800. 



Figure 102. — Longitudinal section of older embryo, showing the 

 outlines of the original segments and the beginning of the 

 formation of dermatogen, at least in the terminal segment, at 

 left. X 800. 



Figure 103. — Longitudinal section of embryo with a diameter of 

 about 0.05 mm.; showing rather irregular segment lines, and 

 globular form of embryo. X 800. 



Figure 104. ^Longitudinal section of embryo of a diameter of about 

 0.075 mm. ; showing increase in size of all cells, but only a 

 slightly greater number than in figure 10.S. X 800. 



Figure 105.— Longitudinal section of embrj'o measuring about 

 0.085 mm, in length ; showing commencement of elongation, 

 and divisions in the terminal segment, at the left, indicating 

 approach of cotyledonary development. X 300. 



Figure 106.— Longitudinal section of embryo measuring about 

 0.135 mm. in length; segment limits obscure; apparently the 

 terminal segment is commencing the formation of stem as well 

 as cot3'ledon. Basal portion shows cells which go to form the 

 rudimentary primary root. X 375. 



