PLATE IX. 



FIGS. 95-96. The generative cell in the early stages of its division, showing 

 granular condensation and radial arrangement of cytoplasm. The 

 spindle fibers arise in the cytoplasmic condensation and extend in the 

 form of a cone to the nuclear membrane. X 744- Pinus rigida. 

 June 8 and 10, 1898. 



97. A cross-section through the generative cell during an early stage in 

 its mitosis. The protoplasmic condensation is seen from below 

 looking toward the nucleus. X 744- Pinus austriaca. June 4, 1898. 



98. A later stage in the division of the generative nucleus. X 744- Pinus 

 austriaca, June 10, 1898. 



99. The generative cell just before the disappearance of the lower portion 

 of the nuclear membrane showing a single deep indentation on the 

 lower side of the nucleus. X 744- Pinus Strobus. June 9, 1898. 



100. A stage in spindle-formation directly following that shown in fig. 99. 

 The nuclear membrane has given way and the spindle fibers are enter- 

 ing the nuclear cavity. The nucleolus is still distinctly visible. 

 X 744- Pinus Strobus. June 10, 1898. 



101. The gradual disappearance of the nuclear membrane and the extension 

 of the spindle fibers across the nucleus. X 744- Pinus austriaca. 

 June 7, 1898. 



102-103. Further development of the spindle and the formation of the 

 chromosomes. The marked condensation in the cytoplasm from 

 which the spindle arose has almost entirely disappeared. X 744- 

 Pinus austriaca. June 8, 1898. 



(172) 



