1918] NOTHNAGEL—FERTILIZATION 147 
while in the collection of May 26 dividing endosperm nuclei and 
second division of the fertilized egg were found for the first time. 
Lilium Martagon, collected from the garden of Indiana University, 
Bloomington, Indiana, in May 1916, 96 and 120 hours after pollina- 
tion, was more favorable for the first division of the endosperm 
nucleus. The former material was killed and fixed in chrom-osmic- 
acetic acid 1-2 hours and then in chromo-acetic acid 24-36 hours, 
washed, dehydrated, and imbedded either from chloroform or xylol. 
Lilium Martagon ovaries were killed and fixed in chrom-osmic- 
acetic acid 24-36 hours, washed, dehydrated, and imbedded from 
chloroform. All sections were cut 12m thick and both modified 
triple and Heidenhain’s iron-alum-haematoxylin were used for 
staining, the latter being more satisfactory for most stages, as the 
chromatin was more sharply differentiated. 
Formation of the primary endosperm nucleus 
For the development of the spirem and the first division of the 
endosperm nucleus, Lilium M artagon was found to be very favor- 
able, as many dividing primary endosperm nuclei were found in the 
sacs of material killed 96 and 120 hours after pollination. Activity 
did not cease at the end of the first divisions, for as many as 12-16 
nuclei were found in many sacs of the older material (fig. 29). 
The sperm comes in contact with the polar nuclei before these 
two have fused, although they may be in contact or in close proxim- 
ity (fig. 17). These three nuclei will usually be found in the center 
of the sac where just previous to the triple fusion the two polar 
nuclei were to be seen. 
The chromatin of the egg can scarcely be said to be in a network, 
but rather to consist of strands which are more or less united 
(figs. 17, 18), that of the male nucleus being much coarser than that 
of the polar nuclei. When the sperm reaches the middle of the 
Sac, it still has its curved or vermiform shape, while the contour 
of the polar nuclei may vary, sometimes being quite curved before 
coming together (fig. 17), but at other times only changing to 
this shape as pressure is exerted by contact. The three nuclei 
upon uniting may be variously twisted about each other, the male 
nucleus usually twisting more than the others and recognizable by 
