PLATE XVI. 



Pittus Styobus unless otherwise indicated. 

 Fig. 167. Telophase in the division of a cell of the spongy tissue. X Sio- 



168. The macrospore and some of the cells of the spongy tissue in the 



first stages of disintegration and having the appearance of a group of 



sporogenous cells. (»?«c.) macrospore. X 96. Pinus austriaca. 

 169-175. Stages in the early development of the archegonium. The 



central cell remains close beneath the neck cells. The cytoplasm is 



very vacuolate. X 140. 



Fig. 169, May 26, 1890; fig. 171, May 31, 189S. 

 176-179. Later stages in the growth of the archegonium. The vacuoles 



gradually disappear and many proteid vacuoles arise in the cytoplasm. 



X 62. Fig. 178 collected June 15, 1S99. 



180. Mature archegonium. The nucleus has assumed a central position in 

 the cell ; the ventral canal-cell is in an advanced stage of disintegration ; 

 the proteid vacuoles are distributed about the periphery especially 

 along the basal portion of the egg, the receptive vacuole has appeared 

 but has not yet assumed its mature or final shape. X 62. June 17, 

 1899. 



181. Nucleus of the central cell shortly before its division. This nucleus 

 is almost invariably concave on the side towards the neck cells. X472. 



182-184. Prophases in the division of the central cell. X 472- Fig. 1S4, 

 Pi?itiS austriaca. 



(186) 



