THE AMERICAN NATURALIST [Vol. XLI 



<lin^ of the ])oll(>n or inicrospores, in spite of the fact that the 

 iiiatenal represents a single collection. A figure 1, represents 

 the first mitosis in tiie microspore, which it will be observed is 

 well advanced towai-d completion. The state of preservation of 

 this material is remarkable in view of the fact that it was fixed 

 m strong alcohol. In /; fignre 1, is to be seen the first prothallial 

 cell fnlly formed and lying over against the Uj)per or poKicrior side 

 of the microspore, lieneath it, is the residual mu lens surrounded 

 by vacuolated protoplasm. In c figure 1, is to b<> seen the mitosis 

 which precedes the formation of the second prothalhal cell. In d 



figure 1, the second prothallial cell is complete and lies against the 

 first. At about thi^ time the .trough thickened posterior ^^all of 

 the microspore, which s(^ems to be a peculiar f(>atin'e of podocar- 

 pineous pollen, becomes markedly sculptured as is shown in (L In 

 a figure 2, is shown a still later phase where the s(»-( alle(l ncuera- 

 tive cell has become added to the prothallial cells, which he on the 

 posterior wall of the microspore; it arises from iuioilier (hvision of 

 the residual nucleus. The contents of the pnlh n ui.uu .u thi> .t.me 

 resemble in detail the conditions to Ik- tound ui the aluetuicdus 

 microspore before the prothallial cells have begun to degenerate. 



