CONIFERALES (PINACEAE) 



273 



of the first in details, and the two lenticular cells disorganize rapidly 

 (fig. 310), become flattened against the spore wall, and very soon 



Figs. 302-313. — Pinus Laricio: a series from the formation of tetrads to the 

 development of the pollen tube; ^, prothallial cells; ^, stalk cell; b, body cell; <, tube 

 nucleus; figs. 302, 303, May 3; fig. 304, May 10; figs. 305-308, May 20; figs. 309-311, 

 May 25; fig. 312, June 15; fig. 313, May i, nearly a year after the stage shown in 

 fig. 312; the exine (c) is shaded with short radial lines, and the intine (i) with longi- 

 tudinal lines; X600. 



