470 BOTANICAL GAZETTE [DECEMBER 
segments medianly, that is, at the apex of the loop; 2x pairs of seg- 
ments result; these separate to form 4x* chromosomes; a new 
spindle is formed and 2% chromosomes pass to each pole. 
5. Fertilization may be regarded as having three phases: (1) sex 
nuclei enter a common cytoplasm; (2) the two groups of chromo- 
somes enter a common nuclear membrane; (3) the chromosomes 
approximate in pairs. The first phase may be prolonged, as in 
Uredineae; the second may be prolonged, as in some animals; or 
the three phases may follow one another in rapid succession, as in 
Abies. Attention is drawn to the similarity existing between the 
phenomena connected with pairing in Abies and tetrad formation 
in animals. It is suggested that they may be like sg pees occur- 
ring at different stages of the life history. 
I wish to express my thanks for many suggestions and helpful 
criticisms given by Professor J. M. Courter and Professor C. J. 
CHAMBERLAIN, under whose direction the investigation was 
pursued. 
UNIVERSITY OF CHICAGO 
LITERATURE CITED 
1. BLACKMAN, V. H., On fertilization, alternation of generations, and general 
cytology of the Uyedinnne: Ann. Botany 18:323-326. 1904 
, On the cytological features of fertilization and related phenomena 
in Pines silvestris. Phil. Trans. Roy. Soc. B 190:395-426. 18 
CHAMBERLAIN, C. J., Oogenesis in Pinus Laricio. Bot. Gaz. 37:268~270. 
sg 
“ 
1899. 
4. COKER, W. C., On the gametophyte and embryo of Taxodium. Bor. Gaz. 
36:1-27. pls. tir. 1903. 
5. FERGUSON, Marcaret C., Contributions to the life history of Pinus, with 
special reference to spurogénesis the development of the gore and 
fertilization. Proc. Wash. Acad. Sci. 6:1-202. pls. I-24. 
6. , The developement of the egg and fertilization in "Pinus Strobus. 
Ann. Botany 153435-479. 1901 
7. GrecorrE, V., Les cinéses ds maturation dans les deux régnes. La 
Cellule 26:223-422. 1910. 
8. Harper, R. A., Sexual reproduction in the organization of the nucleus in 
certain news. Pub. Carnegie. Inst. Wash: no. 37. 1-92. pls. 1-7. 1905- 
9. Hurcutnson, A. H., The male gametophyte of Picea canadensis. Bot. 
GAZ, 59: 287-300. pis. 15-19. fig. I. 1915. 
