42 ALTERNATING GENERATIONS 
These points are illustrated in the Gymnosperms, which the positive 
evidence of the geological record shows to have been the primitive Seed- 
Plants. Since the time of Hofmeister comparative morphology has arrived 
Fic. 28. . 
Pinus Laricio, showing a series from the formation of the tetrads to the development of 
the pollen-tube. , vegetative cells; s¢, stalk cell ; 4, body cell; ¢, tube nucleus. 600. 
(After Coulter and Chamberlain.) 
at the same conclusion, though along a distinct line of argument. Taking 
examples from the Pinaceae, the sporophyte is represented by the Tree, 
which is a large, much-branched, independent, and perennial organism, 
with theoretically unlimited apical growth, and a highly differentiated 
