1915] HUTCHINSON—ABIES BALSAMEA 469 
of the reduced foliage of the abietineous conifers, this [that is, 
resinous secretion] was a very serious drain on the assimilatory 
apparatus. Gradually the more economical tendency arose of 
forming resin passages in the case of need only.” So regarded, 
Pinus would be more primitive than Abies. Whether or not this 
argument is sufficient to overbalance the numerous ancient charac- 
ters of Abies previously tabulated is a matter of judgment which 
we do not presume to decide. 
Many of the foregoing characters are such that they tend to 
relate more closely the two ancient groups of Coniferales, the 
Abietineae and the Araucarineae. 
Summary 
1. The male gametophyte-—The polar (‘‘prothallial’’) cells may 
divide mitotically. The body cell divides to form the male — 
while within the spore coat. Under favorable conditions a “‘pro- 
thallial’’ cell may develop as an antheridial cell, a biantheridial 
gametophyte resulting. The male nuclei are equivalent; one fuses 
with the egg nucleus and frequently the other fuses with the ven- 
tral canal cell nucleus. 
2. The ventral canal cell and ventral proembryo.—The ventral 
canal cell nucleus breaks through its wall into the egg cytoplasm, 
enlarges, and fuses with one of the male nuclei. A ventral pro- 
embryo is formed by two successive divisions. 
3. The egg nucleus—The egg nucleus enlarges to 60 times its 
original volume. At the time of fertilization (fig. 28) irregular, 
darkly staining, vacuolate masses, slender filaments pervaded by 
small granules, spindle fibers, and chromatin are differentiated 
within the nuclear membrane. The chromatin is the fundamental 
nuclear substance; the other bodies are accretions gained during 
the growth of the nucleus and excluded from the nuclei of the 
proembryo. 
4. Fertilization and the first division —After fusion two chroma- 
tin groups appear at the base of the egg nucleus; in each 2x chro- 
mosomes become separate; the two original spindles unite; the 
chromosomes approximate to form x pairs; they twist the one about 
the other and become looped; each of the components of a pair 
