PLATE XIV. 



FIGS. 143-144. Two axial rows of three cells each. The upper of the two daugh- 

 ter-cells formed as a result of the heterotypical division has not divided 

 in either case ; a few starch grains in the cells of the axial row and 

 many large ones in the spongy tissue as shown in fig. 143. X 810. 

 Fig. 143. Pinus Strobus y fig. 144, P. rigida. 



145. An axial row of four cells, reconstructed from serial sections. X 810. 

 Pinus austriaca. 



146. A macrospore nucleus surrounded by large starch grains. X^io. 

 Pinus austriaca. 



147. Growth of the functional macrospore ; the peripheral layer of cyto- 

 plasm already established ; the three upper cells of the axial row almost 

 destroyed ; one large cell of the spongy tissue shown. X 810. Pinus 

 austriaca. June 13, 1898. 



148. An axial row of three cells ; the functional macrospore much enlarged, 

 and the two upper cells in an advanced stage of disintegration ; the 

 spongy tissue distinctly differentiated ; the cells along its outer sur- 

 face more or less tabular in outline and many of them badly disorgan- 

 ized. Pathological conditions have just entered in as shown by the 

 reduced amount of cytoplasm in the cells of the spongy tissue and 

 the slight thickening of their walls. X 2 34- P* rigida. June 24, 

 1902. 



149. The first division of the macrospore-nucleus. X 2 34- Pinus Strobus. 

 July 29, 1898. 



150. The karyokinetic figure from the above more highly magnified ; the 

 division conforms to the typic type and shows the one-half number of 

 chromosomes. X 810. 



151. The first two nuclei of the female gametophyte. X 2 34- Pinus aus- 

 triaca. July 29, 1898. 



152. The four-nucleated stage of the female gametophyte. X 2 34- Pinus 

 Strobus. August 4, 1808. 



153. One of the sixteen free nuclei of a female gametophyte, all sixteen 

 nuclei being in the spireme stage of division. X 810. Pinus Strobus. 

 October 12, 1898. 



154. A vertical section of the central portion of an ovule showing .the 

 spongy tissue and the prothallium with its nuclei, of which there are 

 sixteen, all in the equatorial stage of division ; the prothallium has 

 been somewhat displaced by the action of the fixing fluid. X 46. 

 Pinus Strobus. October 12, 1898. 



155. One of the spindles from the above more highly magnified. X 744- 



(182) 



