466 BOTANICAL GAZETTE [DECEMBER 
A cytological study of fertilization in conifers has been made for 
a number of species: CHAMBERLAIN, Pinus Laricio (3); BLACKMAN, 
Pinus silvestris (2); Miss FErcuson, Pinus (6); MurriL1, Tsuga 
canadensis (20); NOREN, Juniperus (22); and NicHOLs, Juniperus 
(21). ‘‘After the male pronucleus is within the oosphere nucleus 
the chromatin of the two pronuclei appears as two distinct masses 
in the spirem stage” (3). ‘‘Es scheint als wiirde jede der beiden 
Chromatingruppen zuerst ihre eigen Kernspandel ausbilden, die 
sich dann zu einzigen vereinigen”’ (22). On the fibers “‘the long 
bent and twisted chromosomes appear” in Tsuga (20). Miss 
FERGUSON (6) states: “‘When the chromosomes are being oriented 
at the nuclear plate, the maternal and paternal elements can no 
longer be distinguished.” The number of chromosomes at this 
stage was found to be 2x. No count is recorded during the phase 
of pairing (or splitting, as it has generally been regarded). Miss 
FEeRGuSON’s figures confirm what has been described for Abies. 
Her figs. 236 and 237 may be compared with figs. 29-33; her 
fig. 238 with figs. 34-39; and her fig. 241 with fig. 51. As illus- 
trated by diagram B, a number of stages in the process of fertiliza- 
tion have not been described heretofore. It is not surprising that, 
without these stages and not having the chromosome count through- 
out, the pairing should be interpreted as a longitudinal split, and 
that evidence of segmentation should not be found. Because of 
the complete series found in Abies and the extreme size of the 
chromosomes, it has been possible to discover the facts which center 
about the pairing, followed by the transverse segmentation. 
Stages in fertilization —A study of the union of egg and sperm 
in plants and animals makes it evident that there are several phases 
in the process of fertilization. The primary phase is illustrated by 
Uredineae. Here the fusion is evidently incomplete during the 
binucleate stages. ‘In the young aecidium the nuclei become 
paired and divide together in very close association. The teleuto- 
spores in the young state are binucleate, but when mature become 
uninucleate by the fusing of the two paired nuclei” (x). Itis only 
after many separate but simultaneous divisions of the pairing 
nuclei that this second phase of the process is accomplished. 
Harper (8) believes that bivalent chromosomes are formed in 
