ig2o] 



BUCHHOLZ—POLYEMBRYOXl 



155 



segments 



This 



group 



stage 



Next 



pensor cells (s) elongate and thrust the embryonal tier of apical 



embryos have corroded within the 

 gametophyte, the 4 embryo units 

 separating and their apical cells 

 (a) continuing to give rise to segments 

 (e ly e 2 , etc.), which elongate and add 

 to the suspensor. 



Soon the rosette group of initials 



enzymes 



»ment 



mbryos is begu 



1 fa, fig. 8). It 

 will be seen, therefore, that not only 

 do these 8 embryos per zygote all 

 result from free nuclear cleavages, but 

 the several embryos develop inde- 

 pendently from the time the first walls 

 are organized. The primary embryos 

 develop without interruption from 

 their initials, while the rosette em- 

 bryos are delayed, developing some- 

 what later, on an average, than is 

 indicated in fig. 8. In the hundreds 

 of instances that have been examined 



Figs. 6-8. — Stages in develop- 

 ment of early embryo in Pinus: 

 a, apical cells; s, primary suspen- 

 sor cells; r, rosette cells; which 

 give rise to g, rosette embryos 



in my investigations Of various pmes, (i at ter usually develop later than 



none were found where the 4 primary 

 embryos were combined to produce a 



;le embryo, nor were any cases gate and add to suspensor; dia- 



shown) 



etc., embryonal tube initial cells 

 and embryonal tubes, which elon- 



sm 



primary em 



grammatic reconstructions. 



further split up to give rise to 2 or more embn 

 competition which ensues, the rosette embry 



owing 



to their unfavorable position and 



•rnent. Among the 4 primary 

 :ts one embryo from the comp 



pushin 



