1915] HUTCHINSON—ABIES BALSAMEA 4601 
pervaded by fibers radiating from irregular centers (fig. 51). In 
the egg of Abies there is an excessive development of intranuclear 
fibers. It seems reasonable to suppose that they originate from 
cytoplasmic material which has entered the nucleus during its 
growth period, and which may be differentiated into the fibrous 
form under physiological conditions not yet determined. 
The slender filaments pervaded by small granules are scattered 
throughout the greater part of the nucleus. They are most 
definitely organized at the time when the spindle fibers are most 
conspicuous (figs. 27, 33, 42). When the fibers disappear, the fila- 
ments become disorganized, resulting in a granular mass (figs. 43, 
46); when the spindle fibers appear the second time, the whole 
nucleus becomes more or less fibrous (fig. 51); when the daughter 
nuclei are formed, these bodies are not included, but form a matrix 
for the nuclei (figs. 49, 50). _We may conclude that these filaments 
also are cytoplasmic, resembling the spindle fibers in nature, and 
becoming differentiated under similar conditions. 
Pairing of chromosomes in fertilization 
The succession of events which occur in connection with fertili- 
zation and the first division of the zygote has been traced not only 
by a consideration of the stages in the approximation and redistri- 
bution of chromatin bodies, but also by tracing parallel series of 
changes in the size of the nucleus, in the modifications of the deeply 
staining food bodies, and in the formation and dissolution of spindle 
fibers. A study of the chromatin, involving as it does the union 
of the male and female elements and distribution in the daughter 
nuclei, is of primary importance. Emphasis has been given first 
to a study of the related phenomena, already described, thereby 
eliminating, in so far as is possible, the possibility of a misinter- 
pretation of the order of events. 
The approximation of male and female nuclei has been described 
for a number of conifers. In general the process as found in Abies 
agrees with that of these descriptions. A few features may be 
noted. No cytoplasm could be detected adhering to the male 
nucleus as it approached the egg nucleus. There isa great disparity 
in the sizes of the pairing nuclei; that of the egg, as shown in fig. 19, 
