FERTlLIZMIdS 



295 



a conspicuous part in the formation of this "mantle." This phenomenon 

 the significance of which can only be conjectured, is found in Taxodium 

 (Coker 1903), Torrcya californica (Robertson 1901). To,,-, y Q taxifolia 

 (Coulter and Land 1905), Cephalotaxus Fortunei (Coker L907 . Ephedra 

 (Berridge and Sanday 1907; Land 1907), PhyUocladus (Kildahl 1908 

 Juniperus (Nichols 1910), Agathis (Eamea L913), and Taxus (Dupler 

 1917). 



Chromosome Behavior. — The behavior of the chromosomes duri 

 the fusion of the sexual nuclei and the first embryonal division has 

 been described in a number of conifers. As a general rule, to judge from 

 the data at hand, the chromatin contributions of the two pronuclei do 

 not become intimately associated in the fusion nucleus, but remain 

 distinguishable until the first embryonal mitosis occurs. Each of the 

 pronuclei then gives rise to its complement of chromosomes which 





B 



Fig. 120 — Fertilization in I' inns. 



A, male nucleus pressing into female nucleus. X 140. B, first embryonal mitt 

 showing separate paternal and maternal chromosome groups. X 472. {A/U /'■ 

 1904.) 



become arranged, often as two separate groups, upon a common 

 spindle. Such an independent formation of the male and female 

 chromosome groups has been observed in Pinus (Blackmari L898; ( 'hani- 

 berlain 1899; Ferguson 1909, 1904) (Fig. 120), Larix (Woyciki L899 

 Tsuga candensis (Murrill 1900), Juniperus communis (Nore*n L907 . 

 Cunninghamia (Miyake 1910), and Abies (Hutchinson L915 , In 

 Sequoia, on the other hand, Lawson I 1904) reports thai the two nuclei 

 form a common reticulum in which the male and female constituents 

 cannot be distinguished. With regard to the firsl embryonal mitosis 

 the general opinion has been that all the chromosomes, paternal and 

 maternal, split longitudinally, the daughter chromosomes being distri- 

 buted to the daughter nuclei as in any other somatic mitosis. Tin- 

 type of behavior was described for the chromosomes of Pinus by M 

 Ferguson (1904) and at once came to be regarded as general tor .(.in- 

 fers, as it had been for other organisms. 



A new interpretation differing in certain fundamental point.- from the 

 above has been more recently suggested by Hutchinson 1 1915 . as B n suit 



