340 



GYMNOSPERMS 



In a recent paper, Beal^^ describes the first mitosis in the fertilized 

 egg of Finns banksiana (fig. 330). He finds two groups of chromo- 

 somes, as others have found them, and finds that the two spindles 

 quickly merge into one multipolar diarch spindle, on the equator of 

 which the chromosomes lie in one group, with the chromosomes of 



the two gametes indistinguish- 

 ^"^^ able from each other. Each 



chromosome splits longitudi- 

 nally, and the halves pass to 

 the poles, 24 chromosomes to 

 each pole. He finds no pair- 

 ing or transverse segmenta- 

 tion. 



Of course, this does not 

 prove that there is no pairing 

 or transverse segmentation in 

 Abies; and the situation de- 

 scribed for Abies does not 

 prove that there is a pairing 

 and transverse segmentation 

 in Piniis. Both accounts need 

 either confirmation or correc- 

 tion. It seems unlikely that 

 two conifers, in the same 

 family, would differ so de- 

 cidedly. 



Referring again to the first two cases of fertilization in gymno- 

 sperms, described by Strasburger,^'^ in 1878, for Picea vulgaris, 

 and by Coulter,'''^ in 1897, for Pinus laricio, we must note that in 

 both there was doubtless a fertilization of the egg by the nucleus of 

 the ventral canal cell. My own work on Pinus made this interpreta- 

 tion practically a certainty.'"'' Ikeno^** found fertilization of the 

 egg by the ventral canal nucleus in Ginkgo, and Sedgwick^-'^ 

 found that in Encephalartos, in all probability, the same thing 

 occurs. HuTCHiNSON-'^s finds that this occurs occasionally in 

 A bies. 



Fig. 330. — Pinus banksiana: first division 

 of fertilized egg; X150. — From an unpub- 

 lished drawing by J. M. HEAL.-is 



