1897 | LIFE HISTORY OF LILIUM PHILADELPHICUM 447 
often seen on these radiations on their return, and the radiations 
disappear as soon as all the micronucleoli have entered the 
daughter nuclei, as if there remained no further function for 
them. There is no spindle to be formed with which they might 
be associated, as is the case with those around the mother 
nucleus. 
That the central spindle threads are not necessary for the 
formation of the daughter nuclei is shown by the fact that the 
entire central spindle may persist in the cytoplasm for several 
divisions. At some future time the writer hopes to discuss the 
origin of the spindle threads and their relations to the centro- 
somes, 
SUMMARY. 
1. In Litiam Philadelphicum the archesporial cell develops 
directly into the macrospore, and its nucleus during the first- 
- division appears with twelve chromosomes, or half the number 
which are present in the vegetative nuclei. At quite an early 
stage in the development of the macrospore the linin thread of 
the chromatin network begins to thicken, and the chromatin 
granules undergo transverse fission. After division of the 
chromatin granules the whole chromatin band undergoes 
longitudinal splitting, and the double threads thus produced 
begin to twist upon each other. This twisted band finally 
manifests itself as a single continuous spirem, which doubles up 
_ and twists into twelve loops. The twelve loops break apart and 
ive rise to the twelve chromosomes. The two linin threads 
_ With their granules, which compose the loop, continually become 
More intimately associated, so that the loop appears like a 
Single linin thread with two irregular rows of chromatin gran- 
ules. The chromatin loops become shorter by contraction, and 
‘Teceive a thick deposit of some substance which stains light at 
‘Arst but later takes the same color as the chromatin, giving the 
chromosomes the appearance of homogeneous, somewhat irreg- 
ularly bean. shaped bodies, in which the original chromatin 
loop is rarely visible The chromosomes arrange themselves in 
