CONIFERALES (PINACEAE) 281 



In Pinus (65, 87) no wall is formed at the division of the body cell, 

 the two male nuclei being free in the general cytoplasm, and one of 

 them, according to Miss Ferguson (87), soon becoming much larger 

 than the other; a condition also observed in Pseudotsuga (156). In 

 Picea excelsa (79) a cell plate appears on the spindle of the dividing 

 body cell and at once disappears, leaving the two male nuclei free 

 in the general cytoplasm. Just how far this tendency to eliminate 

 one of the male cells has gone among the Abietineae remains to be 

 discovered. An interesting test of this view has recently been sup- 

 plied by IvAWSON (175) in his study of Sciadopitys. The other 

 genera of Taxodineae investigated have the archegonial complex and 

 equal male cells; while Sciadopitys has no archegonial complex and 

 unequal male cells. It is possible to mistake inequality of cells and of 

 nuclei in preparations, so that unusual care will be needed in accumu- 

 lating these facts, but the tendency is evident enough. In Cupressus 

 Goveniana a remarkable situation has been reported (91), the body 

 cell being said to give rise to a cell complex of four to twenty cells, 

 eight or ten cells being the most frequent number (fig. 330). In 

 Juniperus communis the body cell has been observed (173) occasion- 

 ally to produce three or four male cells, but only two of them were 

 considered capable of functioning. The only other cases known 

 among gymnosperms, in which the body cell gives rise to more than 

 two cells, are Microcycas, in which the body cell regularly produces 

 sixteen or more sperms; and Ceratozamia, in which four sperms 

 are formed occasionally (p. 147). The multiplication of male cells 

 in such a form as Cupressus, with its large archegonial complex, might 

 be expected, but at present no conclusions are safe in reference to 

 these rare occurrences. 



The condition of the male gametophyte at the time of pollination 

 is of interest. The records are apt to be misleading if no considera- 

 tion is given to the fact that some tribes have prothallial cells and 

 others do not. So far as observed, the prevailing condition at shed- 

 ding is the stage following the formation of the generative and tube 

 cells. This means after one nuclear division among Taxodineae and 

 Cupressineae, and after three divisions among Abietineae, but it is 

 the same stage in the ontogeny of the gametophyte. Pollination at 

 an earlier stage has been reported for Cupressus (86) and Juniperus 



